Process for helically crimping a fiber

ABSTRACT

Synthetic fiber that are capable of spontaneously transporting water on their surface satisfy the equation 
     
         (1-X cos θ.sub.a)&lt;0, 
    
     wherein 
     θ a  is the advancing contact angle of water measured on a flat film made from the same material as the fiber and having the same surface treatment, if any, 
     X is a shape factor of the fiber cross-section that satisfies the following equation ##EQU1## wherein P W  is the wetted perimeter of the fiber and r is the radius of the circumscribed circle circumscribing the fiber cross-section and D is the minor axis dimension across the fiber cross-section, 
     and wherein the uphill flux value of said fiber is from 2 to 60 cc/g/hr when measured from a reservoir of synthetic urine test fluid along a 20 cm long ramp to an absorbant on an attached platform at 10 cm height.

This is a divisional application of application Ser. No. 08/133,426,filed Oct. 8, 1993, now U.S. Pat. No. 5,611,981 which is a divisionalapplication of Ser. No. 07/736,267, filed Jul. 23, 1991, which is acontinuation-in-part application of Ser. No. 07/333,651, filed Apr. 4,1989, now abandoned.

FIELD OF THE INVENTION

This invention concerns fibers that are capable of spontaneouslytransporting water on their surfaces and useful structures made fromsuch fibers.

BACKGROUND OF THE INVENTION

Presently available absorbant articles such as diapers, sanitarynapkins, incontinence briefs, and the like are generally very good atabsorbing aqueous fluids such as urine and blood. However, duringtypical use such articles become saturated at the impingement zone whileother zones removed from the impingement zone will remain dry. As aresult, a substantial portion of the total absorbant capabilities ofsuch articles remains unused. Thus, it would be highly desirable to havea means for transporting the aqueous fluids from the impingement zone toother areas of the absorbant article to more fully utilize the article'stotal absorbant capability. We have discovered such a means by the useof certain fibers that are capable of transporting aqueous fluids ontheir surfaces.

Liquid transport behavior phenomena in single fibers has been studied toa limited extent in the prior art (see, for example, A. M. Schwartz & F.W. Minor, J. Coll. Sci., 14, 572 (1959)).

There are several factors which influence the flow of liquids in fibrousstructures. The geometry of the pore-structure in the fabrics(capillarity), the nature of the solid surface (surface free energy,contact angle), the geometry of the solid surface (surface roughness,grooves, etc.), the chemical/physical treatment of the solid surface(caustic hydrolysis, plasma treatment, grafting, application ofhydrophobic/hydrophilic finishes), and the chemical nature of the fluidall can influence liquid transport phenomena in fibrous structures.

The ability to transport liquids (alternately referred to herein as"wickability") and to hold liquids are two important features ofabsorbant cores of sanitary consumer disposables such as diapers, adultincontinent products, and feminine hygiene products. Absorbant cores aredesigned to wick fluids as far as possible to prevent leakage andoptimize the use of absorbant material. In a conventional diaper, fluidis wicked by capillary action through the porous fluff pulp core. Liquidholding capacity is largely within the pores of the fluff pulp but isalso enhanced by the addition of superabsorbant polymers to theabsorbant core. These superabsorbant polymers are especially beneficialfor holding liquids under pressure compared to pulp alone. Absorbantcores of diapers and adult incontinent products do not sufficiently wickfluids from the crotch area to entirely prevent leaking. Typically 3-7%of diapers, approximately 30% of feminine napkins, and 33-40% of adultincontinent products leak. Leaking is the number one customer complaintabout these products. Solving the leaking problem is high priority amongthe manufacturers of these products.

In the prior art thermally bonded webs composed of polyester,polypropylene, or polyethylene hydrophobic fibers are formed. These websare subsequently coated with acrylic acid partially neutralized byalkali metallic salts and crosslinked simultaneously with polymerizationto form webs coated in situ with superabsorbant polymer (European PatentApplication 0 223 908). The webs have increased absorption of fluid whenused in a sanitary product such as a diaper, but the individual fibersof the web do not possess the ability to wick fluid from the crotch area(which is most prone to leaking) to lesser utilized areas of theabsorbant core.

French Patent 955,625, Paul Chevalier, "Improvements in SpinningArtificial Fiber", published Jan. 16, 1950, discloses fibers ofsynthetic origin with alleged improved capillarity. The fibers are saidto have continuous or discontinuous grooves positioned in thelongitudinal direction.

Japanese Patent Laid-Open No. 204,975/1984 describes the coating ofcellulose fiber based material with a water soluble monomer which isconverted into a water-absorptive polymer. According to U.S. Pat. No.4,721,647 this type of material has poor absorption performance becausethe monomer is able to penetrate inside the fiber base material and fillthe capillaries between filaments. The mode of wicking in this prior artis totally in the capillaries between the fibers. The diameter of thecapillaries is reduced by the coating. As the coating swells in the wetstate the capillaries are blocked off.

Also, the art discloses various H-shapes as follows:

U.S. Pat. No. 3,121,040 entitled "Unoriented

Polyolefin Filaments" dated Feb. 11, 1964;

U.S. Pat. No. 3,650,659 entitled "Spinning Die" dated Mar. 21, 1972;

U.S. Pat. No. 870,280 entitled "High Bulk Filamentary Material" datedJun. 14, 1961;

U.S. Pat. No. 4,179,259 entitled "Spinneret for the Production ofWool-like Man-Made Filament" dated Dec. 18, 1979;

U.S. Pat. No. 3,249,669 entitled "Process for Making Composite PolyesterFilaments" dated Mar. 16, 1964;

U.S. Pat. No. 3,623,939 entitled "Crimped Synthetic Filament HavingSpecial Cross-Sectional Profile" dated Jun. 28, 1968;

U.S. Pat. No. 3,156,607 entitled "Lobed Filament" dated Nov. 10, 1964;

U.S. Pat. No. 3,109,195 entitled "Spinneret Plate" dated Nov. 5, 1963;

U.S. Pat. No. 3,383,276 entitled "Extruded Synthetic Filament" datedMar. 10, 1964;

Netherlands Abstract OCTROO1N°8490, Aunvrage No. 18049, dated Nov. 28,1922.

U.S. Pat. No. 4,707,409 entitled "Spinneret Orifices and Four-WingFilament Cross-Sections Therefrom" dated Nov. 17, 1987, assigned toEastman Kodak Company, describes a spinneret having an orifice definedby two intersecting slots. Each intersecting slot is in turn defined bythree quadrilateral sections connected in series.

Further, PCT International Publication No. WO90/12/30, published on Oct.18, 1990, entitled "Fibers Capable of Spontaneously Transporting Fluids"by Phillips et al. discloses fibers that are capable of spontaneouslytransporting water on their surfaces and useful structures made fromsuch fibers.

Also, conventional crimping of fibers is done mechanically with astuffer box crimper. This method can damage or distort the cross-sectionof the fibers of this invention. This distortion of the cross-sectionreduces the ability of the fiber to move and hold fluids.

There are various methods of helically crimping a fiber in the art. Forexample, U.S. patent application Ser. No. 07/333,651 filed Apr. 4, 1989describes crimped staple fibers and the process for making the fibers.U.S. Pat. No. 3,050,821 describes a high bulk textile material after arelaxing treatment. U.S. Pat. No. 3,681,188 describes apoly(trimethylene terephthalate) textile fiber in a helical crimp form.U.S. Pat. No. 3,584,103 describes a process for making a helicallycrimped poly(trimethylene terephthalate) fiber with asymmetricbirefringical across the diameter of the filament. U.S. Pat. No.3,623,939 discloses a crimped synthetic filament. The H-shapedcross-section of the fiber is shown.

We have discovered fibers that have a unique combination of propertiesthat allows for spontaneous transport of aqueous fluids such as water ontheir surfaces. Heretofore, fibers capable of spontaneously transportingaqueous fluids such as water have been unknown. These fibers can becoated with superabsorbing polymers which are capable of absorbingliquid as well as transporting liquid. Even more preferably, fibershaving both a major and minor symmetrical axis are quenched by air wherethe air stream is perpendicular to the major axis of the fiber.

SUMMARY OF THE INVENTION

The present invention is directed to a synthetic fiber which is capableof spontaneously transporting water on the surface thereof. The fibersatisfies the following equation

    (1-X cos θ.sub.a)<0,

wherein

θ_(a) is the advancing contact angle of water measured on a flat filmmade from the same material as the fiber and having the same surfacetreatment, if any,

X is a shape factor of the fiber cross-section that satisfies thefollowing equation ##EQU2## wherein P_(W) is the wetted perimeter of thefiber, r is the radius of the circumscribed circle circumscribing thefiber cross-section and D is the minor axis dimension across the fibercross-section.

The present invention also provides a synthetic fiber which is capableof spontaneously transporting water on the surface thereof wherein saidfiber satisfies the equation

    (1-X cos θ.sub.a)<-0.7,

wherein

θ_(a) is the advancing contact angle of water measured on a flat filmmade from the same material as the fiber and having the same surfacetreatment, if any,

X is a shape factor of the fiber cross-section that satisfies thefollowing equation ##EQU3## wherein P_(W) is the wetted perimeter of thefiber, r is the radius of the circumscribed circle circumscribing thefiber cross-section and D is the minor axis dimension across the fibercross-section.

The present invention also further provides a synthetic fiber which iscapable of spontaneously transporting water on the surface thereofwherein said fiber satisfies the equation

    (1-X cos θ.sub.a)<0,

wherein

θ_(a) is the advancing contact angle of water measured on a flat filmmade from the same material as the fiber and having the same surfacetreatment, if any,

X is a sahpe factor of the fiber cross-section that satisfies thefollowing equation ##EQU4## wherein P_(W) is the wetted perimeter of thefiber and r is the radius of the circumscribed circle circumscribing thefiber cross-section and D is the minor axis dimension across the fibercross-section,

and wherein the uphill flux value of said fiber is from about 2 to 60cc/g/hr when measured from a reservoir of synthesis urine test fluidalong a 20 cm long ramp to an absorbant on an attached platform at 10 cmheight.

The present invention even further provides a synthetic fiber which iscapable of spontaneously transporting water on the surface thereofwherein said fiber satisfies the equation

    (1-X cos θ.sub.a)<0,

wherein

θ_(a) is the advancing contact angle of water measured on a flat filmmade from the same material as the fiber and having the same surfacetreatment, if any,

X is a shape factor of the fiber cross-section that satisfies thefollowing equation ##EQU5## wherein P_(W) is the wetted perimeter of thefiber, r is the radius of the circumscribed circle circumscribing thefiber cross-section and D is the minor axis dimension across the fibercross-section, with the proviso that the fiber is not an X-shaped or anH-shaped fiber having a θ_(a) of about 22 degrees, cos θ_(a) of about0.9, and an X factor of about 1.8.

It is preferred that ##EQU6## wherein γ_(LA) is the surface tension ofwater in air in dynes/cm, σ is the fiber density in grams/cc, and dpf isthe denier of the single fiber.

It is preferred that X is greater than 1.2, preferably between about 1.2and about 5, most preferably between about 1.5 and about 3. It ispreferred that the fiber have an uphill flux value of about 2 to about60 cc/g/hr.

It is also preferred that the fiber is helically crimped which isobtained by quenching in air which is flowing perpendicular to the majoraxis of the fiber.

Further, it is preferred that the fiber has a hydrophilic lubricantcoated on the surface thereof.

FIG. 1A--illustration of the behavior of a drop of an aqueous fluid on aconventional fiber that is not spontaneously transportable after theellipsoidal shape forms (t=0). Angle θ illustrates a typical contactangle of a drop of liquid on a fiber. The arrows labelled "LFA" indicatethe location of the liquid-fiber-air interface.

FIG. 1B--illustration of the behavior of a drop of an aqueous fluid on aconventional fiber that is not spontaneously transportable at time=t₁(t₁ >0). The angle θ remains the same as in FIG. 1A. The arrows labelled"LFA" indicate the location of the liquid-fiber-air interface.

FIG. 1C--illustration of the behavior of a drop of an aqueous fluid on aconventional fiber that is not spontaneously surface transportable attime=t₂ (t₂ >t₁). The angle θ remains the same as in FIG. 1A. The arrowslabelled "LFA" indicate the location of the liquid-fiber-air interface.

FIG. 2A--illustration of the behavior of a drop of an aqueous fluidwhich has just contacted a fiber that is spontaneously transportable attime =0. The arrows labelled "LFA" indicate the location of theliquid-fiber-air interface.

FIG. 2B--illustration of the behavior of a drop of an aqueous fluid on afiber that is spontaneously transportable at time=t₁ (t₁ >0). The arrowslabelled "LFA" indicate the location of the liquid-fiber-air interface.

FIG. 2C--illustration of the behavior of a drop of an aqueous fluid on afiber that is spontaneously transportable at time=t₂ (t₂ >t₁). Thearrows labelled "LFA" indicate the location of the liquid-fiber-airinterface.

FIG. 3--schematic representation of an orifice of a spinneret useful forproducing a spontaneously transportable fiber.

FIG. 4--schematic representation of an orifice of a spinneret useful forproducing a spontaneously transportable fiber.

FIG. 5--schematic representation of an orifice of a spinneret useful forproducing a spontaneously transportable fiber.

FIG. 6--schematic representation of an orifice of a spinneret useful forproducing a spontaneously transportable fiber.

FIG. 6B--schematic representation of an orifice of a spinneret usefulfor producing a spontaneously transportable fiber.

FIG. 7--schematic representation of an orifice of a spinneret having 2repeating units, joined end to end, of the orifice as shown in FIG. 3.

FIG. 8--schematic representation of an orifice of a spinneret having 4repeating units, joined end to end, of the orifice as shown in FIG. 3.

FIG. 9--photomicrograph of a poly(ethylene terephthalate) fibercross-section made using a spinneret having an orifice as illustrated inFIG. 3 (specific dimensions of spinneret orifice described in Example1).

FIG. 10--photomicrograph of a polypropylene fiber cross-section madeusing a spinneret having an orifice as illustrated in FIG. 3 (specificdimensions of spinneret orifice described in Example 2).

FIG. 11--photomicrograph of a nylon 66 fiber cross-section made using aspinneret having an orifice as illustrated in FIG. 3 (specificdimensions of spinneret orifice described in Example 2).

FIG. 12--schematic representation of a poly(ethylene terephthalate)fiber cross-section made using a spinneret having an orifice asillustrated in FIG. 4 (specific dimensions of spinneret orificedescribed in Example 8).

FIG. 13--photomicrograph of a poly(ethylene terephthalate) fibercross-section made using a spinneret having an orifice as illustrated inFIG. 5 (specific dimensions of spinneret orifice described in Example9).

FIG. 14--photomicrograph of a poly(ethylene terephthalate) fibercross-section made using a spinneret having an orifice as illustrated inFIG. 7 (specific dimensions of spinneret orifice described in Example10).

FIG. 15--photomicrograph of a poly(ethylene terephthalate) fibercross-section made using a spinneret having an orifice as illustrated inFIG. 8 (specific dimensions of spinneret orifice described in Example11).

FIG. 16--schematic representation of a fiber cross-section made using aspinneret having an orifice as illustrated in FIG. 3 (Example 1).Exemplified is a typical means of determining the shape factor X.

FIG. 17--photomicrograph of a poly(ethylene terephthalate) fibercross-section made using a spinneret having an orifice as illustrated inFIG. 6 (specific dimensions of spinneret orifice described in Example12).

FIG. 17B--schematic representation of a poly(ethylene terephthalate)fiber cross-section made using a spinneret having an orifice asillustrated in FIG. 6B (specific dimensions of spinneret orificedescribed in Example 13).

FIG. 18A--a schematic representation of the top view of a diaper.

FIG. 18B--a schematic representation of an exploded side view of adiaper along section 1B of the major axis of the diaper.

FIG. 19--a schematic representation of an exploded side view of a diaperalong the major axis of the diaper. The tow made from fibers of thepresent invention is placed below the top sheet and above the absorbantcore.

FIG. 20--a schematic representation of an exploded side view of a diaperalong the major axis of the diaper. The tow made from fibers of thepresent invention is placed below the absorbant core and above the backsheet.

FIG. 21--a schematic representation of an exploded side view of a diaperalong the major axis of the diaper. The tow made from fibers of thepresent invention is placed within the absorbant core.

FIG. 22--a schematic representation of an exploded side view of a diaperalong the major axis of the diaper. The staple fibers made from fibersof the present invention is in the absorbant core.

FIG. 23A--a schematic representation of the top view of a diaper. Thelines in the cut-away view represent tow made from fibers of the presentinvention which are substantially parallel and running essentially theentire length of the diaper.

FIG. 23B--a schematic representation of the top view of a diaper. Thelines in the cut-away view represent tow made from fibers of the presentinvention which are substantially parallel and extending more than halfthe length of the diaper.

FIG. 24--a schematic representation of the top view of a diaper. Thelines in the cut-away view represent tightly compacted tow (made fromfibers of the present invention) in the impingement zone and the tow isflared at the end.

FIG. 25--a schematic representation of the top view of a diaper. Thelines in the cut-away view represent tow made from fibers of the presentinvention. The major axis of the tow is inclined at an angle of 30° withrespect to the major axis of the diaper.

FIG. 26--a schematic representation of an exploded side view of a diaperalong the major axis of the diaper. The tow made from fibers of thepresent invention is placed above and below the absorbant core.

FIG. 27--graph of the ink holding capacity in grams (g) versus cartridgedensity in grams per cubic centimeter (g/cc) for an ink cartridge madefrom fibers of the present invention (line labeled "4SW") and for an inkcartridge made from fibers of the prior art of round cross-section (linelabeled "round").

FIG. 28--graph of the percent ink remaining versus cartridge density(g/cc) for an ink cartridge made from fibers of the present invention(line labeled "4SW") and for an ink cartridge made from fibers of theprior art of round cross-section (line labeled "round").

FIG. 29--graph of the useable ink (g) versus cartridge density (g/cc)for an ink cartridge made from fibers of the present invention (linelabeled "4SW") and for an ink cartridge made from fibers of the priorart of round cross-section (line labeled "round").

FIG. 30--graph of the ratio of useable ink (g)/fiber weight (g) versuscartridge density (g/cc) for an ink cartridge made from fibers of thepresent invention (line labeled "4SW") and for an ink cartridge madefrom fibers of the prior art of round cross-section (line labeled"round").

FIG. 31A--a schematic representation of a desirable groove in a fibercross-section.

FIG. 31B--a schematic representation of a desirable groove in a fibercross-section.

FIG. 31C--a schematic representation of a desirable groove in a fibercross-section illustrating the groove completely filled with fluid.

FIG. 32A--a schematic representation of a groove where bridging ispossible in the fiber cross-section.

FIG. 32B--a schematic representation of a groove where bridging ispossible in the fiber cross-section.

FIG. 32C--a schematic representation of a groove illustrating bridgingof the groove by a fluid.

FIG. 33--a schematic representation of a preferred "H" shape orifice ofa spinneret useful for producing a spontaneously transportable fiber.

FIG. 34--a schematic representation of a poly-(ethylene terephthalate)fiber cross-section made using a spinneret having an orifice asillustrated in FIG. 33.

FIG. 35A and 35B--schematic representations of a preferred "H" shapeorifice of a spinneret useful for producing a spontaneouslytransportable fiber (see Example 23). "W" as shown herein is the same as"W₁ " referred to in Example 23.

FIG. 36A and 36B--schematic representations of a preferred "H" shapeorifice of a spinneret useful for producing a spontaneouslytransportable fiber (see Example 23). "W" as shown herein is the same as"W₁ " referred to in Example 23.

FIG. 37--graph of the flux in cc/hr/g vs. channel width (microns) for aplasma treated spontaneously transportable fiber made of poly(ethyleneterephthalate) and having an "H" shape cross-section.

FIG. 38--graph of maximum flux in cc/hr/g vs. adhesion tension for apoly(ethylene terephthalate) having an "H" shape cross-section with twounit cells or channels wherein each channel depth is 143μ and the legthickness of each channel is 10.9μ.

FIG. 39--a schematic representation of the apparatus used to determineuphill flux.

FIG. 40--a schematic representation depicting a unit cell.

FIG. 41A and 41B--a schematic representations of a spinneret havingdimensions as specified.

FIG. 42A 42B and 42C--a schematic representations of Spinneret I1045wherein the spinneret holes are oriented such that the cross-flow quenchair is directed toward the open end of the H. All dimensions are inunits of inches except those containing the letter "W".

FIG. 43A and 43B--schematic representations of Spinneret I1039 whereinthe spinneret holes are oriented in a radial pattern on the face of thespinneret. All dimensions are in units of inches except those containingthe letter "W".

FIG. 44--a photomicrograph of stuffer box crimped fiber having adistorted cross-section.

FIG. 45--a photomicrograph of a cross-section of a helically crimpedfiber formed by the process of helically crimping a fiber of thisinvention wherein the fiber cross-section is not distorted.

FIG. 46A, 46B and 46B--schematic representations of Spinneret I1046wherein the spinneret holes are oriented such that the cross-flow quenchair is directed toward the open end of the H.

FIG. 47--a schematic representation of quench air direction relative tothe spinneret holes.

FIG. 48A, 48B and 48C--schematic representations of Spinneret 1047wherein spinneret holes are oriented such that the cross-flow quench airwas directed toward one side of the H.

FIG. 49--a photomicrograph of helically crimped fibers of the inventionwithout a distorted cross-section.

FIG. 50--a photomicrograph of stuffer box crimped fiber having adistorted cross-section.

FIG. 51A, 51B and 52--schematic representations of a spinneret whereinthe spinneret holes are oriented in a diagonal pattern on the face ofthe spinneret with cross-flow quenching directed toward the fiberbundle.

FIG. 53--a photomicrograph of a helically crimped fiber prepared by theprocess of the invention.

FIG. 54--a schematic representation of the programming of the computerused in the uphill flux test.

FIG. 55--a schematic representation of a single fiber with one groovefilled with superabsorbant polymer.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, the term "base fibers" means the fibers disclosed inSer. No. 333,651 not having a superabsorbant polymer coating (butoptionally having a different surface treatment, e.g., a coating of ahydrophilic lubricant), and the terms "coated fiber", "absorbant fiber",or "coated, absorbant fiber" mean a fiber of the present invention,i.e., a base fiber having coated thereon at least one superabsorbantpolymer.

The three important variables fundamental to the liquid transportbehavior are (a) surface tension of the liquid, (b) wettability or thecontact angle of the liquid with the solid, and (c) the geometry of thesolid surface. Typically, the wettability of a solid surface by a liquidcan be characterized by the contact angle that the liquid surface(gas-liquid interface) makes with the solid surface (gas-solid surface).Typically, a drop of liquid placed on a solid surface makes a contactangle, θ, with the solid surface, as seen in FIG. 1A. If this contactangle is less than 90°, then the solid is considered to be wet by theliquid. However, if the contact angle is greater than 90°, such as withwater on Teflon® surface, the solid is not wet by the liquid. Thus, itis desired to have a minimum contact angle for enhanced wetting, butdefinitely, it must be less than 90°. However, the contact angle alsodepends on surface inhomogeneities (chemical and physical, such asroughness), contamination, chemical/physical treatment of the solidsurface, as well as the nature of the liquid surface and itscontamination. Surface free energy of the solid also influences thewetting behavior. The lower the surface energy of the solid, the moredifficult it is to wet the solid by liquids having high surface tension.Thus, for example, Teflon, which has low surface energy does not wetwith water. (Contact angle for Teflon-water system is 112°.) However, itis possible to treat the surface of Teflon with a monomolecular film ofprotein, which significantly enhances the wetting behavior. Thus, it ispossible to modify the surface energy of fiber surfaces by appropriatelubricants/finishes to enhance liquid transport. The contact angle ofpolyethylene terephthalate (PET), Nylon 66, and polypropylene with wateris 80°, 71°, and 108°, respectively. Thus, Nylon 66 is more wettablethan PET. However, for polypropylene, the contact angle is >90°, andthus polypropylene is nonwettable with water.

The second property of fundamental importance to the phenomena of liquidtransport is surface tension of the liquid.

The third property of fundamental importance to the phenomena of liquidtransport is the geometry of the solid surface. Although it is knownthat grooves enhance fluid transport in general, we have discoveredparticular geometries and arrangements of deep and narrow grooves onfibers and treatments thereof which allow for the spontaneous surfacetransport of aqueous fluids in single fibers. Thus we have discoveredfibers with a combination of properties wherein an individual fiber iscapable of spontaneously transporting water on its surface.

Geometry of the fiber surface and application of a hydrophilic lubricantare very important. Also, the particular geometry of the deep and narrowgrooves is very important. For example, as shown in FIGS. 31A, 31B and31C, grooves which have the feature that the width of the groove at anydepth is equal to or less than the width of the groove at the mouth ofthe groove are preferred over those grooves which do not meet thiscriterion (e.g., grooves as shown in FIGS. 32A, 32B and 32C). If thepreferred groove is not achieved, "bridging" of the liquid across therestriction is possible and thereby the effective wetted perimeter(P_(w)) is reduced. Accordingly, it is preferred that P_(W) issubstantially equal to the geometric perimeter.

The number of continuous grooves present in the fiber of the presentinvention is not critical as long as the required geometry is present(i.e., the fiber satisfies the equation (1-X cos θ_(a))<-0.7); or (1-Xcos θ_(a))<0) with the proviso that the fiber is not an X-shaped or anH-shaped fiber having a θ_(a) of about 22 degrees, cos θ_(a) of about0.9, and an X factor of about 1.8; or (1-X cos θ_(a))<0 wherein theuphill flux value of said fiber is from about 2 to about 60 cc/g/hr whenmeasured from a reservoir of synthetic urine test fluid along a 20 cmlong ramp to an absorbant on an attached platform at 10 cm height. Theterm "about" is defined for the purposes of this equation as beingwithin plus or minus 5% experimental error. Typically there are at least2 grooves present, and preferably less than 10.

"Spontaneously transportable" and derivative terms thereof refer to thebehavior of a fluid in general and in particular of a drop of fluid,typically water, when it is brought into contact with a single fibersuch that the drop spreads along the fiber. Such behavior is contrastedwith the normal behavior of the drop which forms a static ellipsoidalshape with a unique contact angle at the intersection of the liquid andthe solid fiber. It is obvious that the formation of the ellipsoidaldrop takes a very short time but remains stationary thereafter. FIGS.1A-1C and 2A-2C illustrate the fundamental difference in these twobehaviors. Particularly, FIGS. 2A, 2B, and 2C illustrate spontaneousfluid transport on a fiber surface. The key factor is the movement ofthe location of the air, liquid, solid interface with time. If suchinterface moves just after contact of the liquid with the fiber, thenthe fiber is spontaneously transportable; if such interface isstationary, the fiber is not spontaneously transportable. Thespontaneously transportable phenomenon is easily visible to the nakedeye for large filaments (>20 denier per filament (dpf)) but a microscopemay be necessary to view the fibers if they are less than 20 dpf.Colored fluids are more easily seen but the spontaneously transportablephenomenon is not dependent on the color. It is possible to havesections of the circumference of the fiber on which the fluid movesfaster than other sections. In such case the air, liquid, solidinterface actually extends over a length of the fiber. Thus, such fibersare also spontaneously transportable in that the air, liquid, solidinterface is moving as opposed to stationary.

Spontaneous transportability is basically a surface phenomenon; that isthe movement of the fluid occurs on the surface of the fiber. However,it is possible and may in some cases be desirable to have thespontaneously transportable phenomenon occur in conjunction withabsorption of the fluid into the fiber. The behavior visible to thenaked eye will depend on the relative rate of absorption vs. spontaneoustransportability. For example, if the relative rate of absorption islarge such that most of the fluid is absorbed into the fiber, the liquiddrop will disappear with very little movement of the air, liquid, solidinterface along the fiber surface whereas if the rate of absorption issmall compared to the rate of spontaneous transportability the observedbehavior will be like that depicted in FIGS. 2A through 2C. In FIG. 2A,a drop of aqueous fluid is just placed on the fiber (time=0). In FIG.2B, a time interval has elapsed (time=t₁) and the fluid starts to bespontaneously transported. In FIG. 2C, a second time interval has passed(time=t₂) and the fluid has been spontaneously transported along thefiber surface further than at time=t₁.

The fibers of the invention preferably have excellent uphill flux.Uphill flux is an index of the rate of transport of a fluid and isdetermined by the methodology described in Example 21 hereof. Uphillflux is related to adhesion tension. Adhesion tension is the product ofthe surface tension γ and cos θ_(a). We have surprisingly found that thetype of fiber surface treatment can have a substantial impact on theeffective adhesion tension (and therefore on the uphill flux). That is,we have found that certain surface treatments have the undesirablefeature of reducing the effective surface tension of aqueous fluids(e.g., urine) such that it is substantially reduced from its theoreticalpotential. Thus, preferred surface treatments are those which result inthe effective adhesion tension of the fluid to be transported being asclose to the theoretical adhesion tension as possible. The effectiveadhesion tension is measured by the method described in Example 22hereof using the appropriate fluid. Preferred fibers of the inventionhave an effective adhesion tension in water of greater than 38 dynes/cm.More preferred is greater than 45 dynes/cm. Plasma treatment is apreferred surface treatment since the effective adhesion tension isclose to the theoretical adhesion tension.

It is not desired to be bound by any particular theory or mechanism.However, it is believed that for some surface treatments, such as use ofpotassium lauryl phosphate and/or PEG 600 monolaurate, a portion of thedeposited surface treatment material partially solubilizes in the fluid,at least at the fluid/surface interface, substantially reducing thesurface tension of the liquid, thereby reducing the effective adhesiontension but not substantially affecting the contact angle (θ_(a)).

It has also been discovered that for a given vertical distance andlinear distance to move the fluid, a given channel depth and a givenadhesion tension, there is an optimum channel width which maximizes theuphill flux of the liquid being transported. A fiber of the inventioncan be characterized as having one or more "channels" or "unit cells".For example, the fiber cross-section shown in FIG. 40 depicts a unitcell. A unit cell is the smallest effective transporting unit containedwithin a fiber. For fibers with all grooves identical, the total fiberis the sum of all unit cells. In FIG. 40 each unit cell has a height, H,and a width, W. S_(l) is the leg thickness and S_(b) is the backbonethickness. In addition to the specific dimensions of W and H, the otherdimensional parameters of the cross-section are important for obtainingthe desired type of spontaneous transportability. For example, it hasbeen found that the number of channels and the thickness of the areasbetween unit cells, among other things, are important for optimizing theuphill flux value of the fiber. For obtaining a fiber cross-section ofdesirable or optimal fluid movement properties the following equationsare useful: ##EQU7## wherein: q=flux (cm³ /hr-gm)

W=channel width (cm)

μ=fluid viscosity (gm/cm-sec)

M_(f) =fiber mass per channel (gm)

ρ_(f) =fiber density (gm/cm³)

A_(f) =fiber cross-sectional area per channel (cm²)

L_(f) =total fiber length (cm)

l=distance front has advanced along fiber (cm)

α=adhesion tension correction factor (surface) (d'less)

γ=fluid surface tension (dynes/cm-gm/sec²)

p=wetted channel perimeter (cm)

H=channel depth (cm)

θ=contact angle (degrees)

β=adhesion tension correction factor (bulk) (d'less)

K=constant (d'less)

ω=arc length along meniscus (cm)

ρ=fluid density (gm/cm³)

g=acceleration of gravity (cm/sec²)

h=vertical distance (cm)

g_(c) =gravitational constant (d'less)

A=fluid cross-sectional area per channel (cm²)

n=number of channels (d'less)

S_(b) =fiber body or backbone thickness (cm)

S_(l) =fiber leg thickness (cm)

e=backbone extension (cm)

φ=fiber horizontal inclination angle (degrees)

dpf=denier per filament (gm/9000 m)

The equation for q is useful for predicting flux for a channeled fiberhorizontally inclined at an angle φ. This equation contains all theimportant variables related to fiber geometry, fiber physicalproperties, physical properties of the fluid being transported, theeffects of gravity, and surface properties related to the three-wayinteraction of the surfactant, the material from which the fiber ismade, and the transported fluid. The equations for M_(f), A_(f), p, ω,h, and A can be substituted into the equation for q to obtain a singlefunctional equation containing all the important system variables, or,for mathematical calculations, the equations can be used individually tocalculate the necessary quantities for flux prediction.

The equation for q (including the additional equations mentioned above)is particularly useful for determining the optimum channel width tomaximize uphill flux (fluid movement against the adverse effects ofgravity; sin φ>0 in the equation for h). The equation for q is alsouseful for calculating values for downhill flux (fluid movement enhancedby gravity; sin φ<0 in the equation for h) for which there is no optimumchannel width. Obviously, horizontal flux can also be calculated (nogravity effects; sin φ=0). The equation for q and the equations for p,A, and A_(f) were derived for a fiber containing one or morerectangularly-shaped channels, but the basic principles used to derivethese equations could be applied to channels having a wide variety ofgeometries.

A fiber of the present invention is capable of spontaneouslytransporting water on the surface thereof. Distilled water can beemployed to test the spontaneous transportability phenomenon. However,it is often desirable to incorporate a minor amount of a colorant intothe water to better visualize the spontaneous transport of the water, solong as the water with colorant behaves substantially the same as purewater under test conditions. We have found aqueous Syltint Poly Red®from Milliken Chemicals to be a useful solution to test the spontaneoustransportability phenomenon. The Syltint Poly Red® solution can be usedundiluted or diluted significantly, e.g., up to about 50×with water.

In addition to being capable of transporting water, a fiber of thepresent invention is also capable of spontaneously transporting amultitude of other aqueous fluids. Aqueous fluids are those fluidscomprising about 50% or more water by weight, preferred is about 75% ormore water by weight, most preferred is about 90% or more water byweight. Preferred aqueous fluids are body fluids, especially human bodyfluids. Such preferred fluids include, but are not limited to, blood,urine, perspiration, and the like. Other preferred aqueous fluidsinclude, for example, aqueous inks.

In addition to being able to transport aqueous fluids, a fiber of thepresent invention is also capable of transporting an alcoholic fluid onits surface. Alcoholic fluids are those fluids comprising greater thanabout 50% by weight of an alcoholic compound of the formula

    R--OH

wherein R is an aliphatic or aromatic group containing up to 12 carbonatoms. It is preferred that R is an alkyl group of 1 to 6 carbon atoms,more preferred is 1 to 4 carbon atoms. Examples of alcohols includemethanol, ethanol, n-propanol and isopropanol. Preferred alcoholicfluids comprise about 70% or more by weight of a suitable alcohol.Preferred alcoholic fluids include antimicrobial agents, such asdis-infectants, and alcohol-based inks.

The superabsorbant coating of the coated fiber of the present inventionacts as a "sink" and absorbs whatever fluid is being transported.

The absorbant fibers of the present invention are coated with at leastone superabsorbant material. By the word "coated" and derivative termsthereof is meant that the superabsorbant material is in a continuousphase and completely surrounds the circumference of a fibercross-section for at least a portion of the fiber length. Differentembodiments of the coating include wherein the entire fiber issubstantially coated and wherein the fiber is only intermittentlycoated. This intermittent coating provides segments which will transportfluid without absorbing it to areas which are coated with superabsorbantpolymer and which will absorb the fluid in a preferred area. Whichspecific embodiment is preferred will depend upon the particular desiredapplication. A particular preferred embodiment is wherein the fiber ofthe present invention is substantially the length of an absorbantarticle (e.g., a diaper, an incontinent pad, or the like) and is coatedon the ends of the fiber, but not in the center portion.

Also, in the coated fibers of the invention, the coating is in intimatecontact with at least a portion of the fiber surface. Preferably,substantially the entire coating which is positioned adjacent to thefiber surface is in intimate contact with that portion of the fibersurface. That is, preferably all the groove surfaces are "filled" and novisible gaps appear between the coating and the fiber surface uponroutine examination by microscopy at a magnification of about 20×.

Water soluble polymerizable monomers such as acrylic acid, methacrylicacid, and vinylsulfonic acid of which 20% or more of the carboxyl groupshave been neutralized into an alkali metal salt can be used to form thesuperabsorbant coating on the base fibers. Preferred superabsorbantpolymers are those formed which have a crosslinked structure. Watersoluble crosslinking agents having two or more functional groups capableof reacting with a functional group of the aforementioned acids can beused. They are well known in the art. N,N'-methylene bisacrylamide,ethylene glycol bisacrylate, and polyglycidyl ethers are typicalexamples. The polymerization is carried out in situ, i.e., in thepresence of the base fibers. The polymerization can be accomplishedthrough thermal, light, accelerated electron beams, radiation,ultraviolet rays. It is necessary to add a water soluble radicalpolymerization initiator, in thermal polymerization, or a water-solubleinitiator capable of generating radicals with the aid of light orultraviolet rays in photopolymerization or ultraviolet polymerization tothe aqueous monomer solution. Initiators are well known in the art (seeU.S. Pat. No. 4,721,647). The degree of crosslinking can be varied tocontrol the amount and rate of absorption to the extent that thesuperabsorbant polymer remains water insoluble. The amount ofsuperabsorbant polymer coating can be varied. It is preferred that theamount be limited so that individual filaments are not bonded togetheror that the swollen gel is prevented from leaving the grooves of thefilaments.

Generally, the methodology taught in U.S. Pat. No. 4,721,647(incorporated herein by reference in its entirety) and European PatentApplication 0 188 091 can be used to prepare the coated absorbant fibersof the present invention except that one would substitute thespontaneously transportable fibers of Ser. No. 333,651, (i.e., the basefibers) for the fiber used in the prior art methods.

A prior art example (European Patent Application 0 188 091) disclosesnon-woven webs having a thin superabsorbant polymeric coating on theindividual fibers of the web. The fibers of this web are roundcross-section fibers such as Kodel® 431 polyester (available fromEastman Chemical Products, Inc., Kingsport, Tenn., U.S.A.). Theaforementioned disclosure attempts to solve the problem of gel blockingwhich occurs in some absorbant products where the superabsorbant polymerin granule form is layered within absorbant core. As the superabsorbantpolymer granules absorb fluid they swell. Liquid transport through theswollen gel is limited primarily to the slow rates of diffusion. TheEuropean Patent Application 0 188 091 attempts to solve this barrierproblem of swollen gels by uniformly dispersing the superabsorbantpolymer throughout the web as a uniformly thin coated film on thefibers. The claim is that they will not block fluid transport throughoutthe remainder of the open network structure of the web. The thinlycoated fibers of 0 188 091 only absorb fluid in the coating. They do notwick fluid. These webs are dependent on the capillary action of thepores between the fibers for wicking action. The coated fibers,filaments, or webs coated with superabsorbant polymer of this inventionunexpectedly both wick and absorb fluid.

The problem of blocking capillary wicking action between superabsorbantcoated hydrophilic fiber base materials discussed in U.S. Pat. No.4,721,647 is not a problem in the present invention since the wickingaction does not depend solely on capillary action between filaments.Furthermore, substantial uniform coating of monomer solution isaccomplished within the grooves of the base fibers as opposed to outerperimeter and between filaments of the prior art hydrophilic fibers.

The liquid transport of the fibers is attributed to having a desiredcombination of hydrophilic coating and surface geometry. One wouldexpect that coating these fibers with superabsorbant polymer (especiallyusing amounts of polymer which completely fill the grooves of the basefibers) would destroy the preferred geometry of the filament necessaryfor liquid transport. Unexpectedly when these base fibers which havebeen coated with superabsorbant polymer are subjected to a fluid such aswater or synthetic urine, the super-absorbant polymer filling thegrooves is observed to swell as it absorbs fluid. The swollen gel popsout of the grooves sufficient to allow the fluid to wick down the opengroove until it contacts additional super-absorbant. The process isrepeated continuously until the superabsorbant is consumed or the end ofthe filament is reached. Although it is not desired to be bound by anyparticular mechanism, it is believed that the hydrophilic coatinginitially placed on the base fibers is not destroyed by thesuperabsorbant polymer coating and the desired geometry of the groovesis restored as the superabsorbant polymer swells and moves out of thegrooves. Also it is believed that no bonding occurs between thesuperabsorbant polymer coating and the fiber surface to hold the gel. Across-sectional schematic of a single base fiber having a groove filledwith superabsorbant polymer is shown in FIG. 55. The superabsorbantpolymer is shown as it swells and pops out of the groove. This actionallows room for more fluid to enter and wick in the groove.

We have discovered an improved process for helically crimping a fiberhaving both a major and a minor axis of symmetry, wherein quenching byair occurs perpendicular to the major axis of the fiber. In particular,the process involves the following steps: extruding a conventional PETfiber forming polymer; passing the polymer through spinneret holeshapes; orienting said spinneret hole shapes to the cross-flow quenchair so that quenching occurs perpendicular to the major axis of thefiber; controlling the quench air; applying hydrophilic lubricants;taking up the fibers at conventional speeds; drafting the fibers usingconventional drafting (single steam stage in steam or two stage in waterand steam); adding an additional amount of hydrophilic lubricant; andrelaxing the drawn fibers in a heated chamber to develop the helicalcrimp.

The full development of the helical crimp in the fibers of the presentinvention is realized by relaxing the fibers in heat. The temperature ofthe heating step is above the T_(g) of the fibers. Also, it appears thatthe helical crimp is formed due to differences in the orientation of thefiber across the diameter of the cross section. This difference inorientation is built into the fiber by following the steps listed in theprocess previously described. The higher the difference in orientation,the more likely that the filament will form a helical crimp.

It is also preferred that the number of crimps/inch in the fiber isgreater than 4 and the crimp amplitude is less than 2 mm.

Particularly preferred hydrophilic lubricants which can be used tolubricate the fibers of this invention include the following:

(1) Lubricant (PM 13430) comprising 49% polyethylene glycol (PEG) 600monolaurate, polyoxyethylene (13.64) monolaurate, 49% polyethyleneglycol (PEG) 400 monolaurate, polyoxyethylene (9.09) monolaurate, and 2%4-cetyl-4-ethylmorpholinium ethosulfate (antistat);

(2) Hypermer A109 sold by ICI Americas, Inc., which is a modifiedpolyester surfactant;

(3) Milease T sold by ICI Americas, Inc. which is a soil release agentcomprising polyester, water, and other ingredients;

(4) Brij 35 sold by ICI Americas, Inc. which is a polyoxyethylene (23)lauryl ether;

(5) Brij 99 sold by ICI Americas, Inc. which is a polyoxyethylene (20)oleyl ether;

(6) G-1300 sold by ICI Americas, Inc. which is a polyoxyethyleneglyceride ester, a nonionic surfactant; and

(7) G-1350 sold by ICI Americas, Inc., a polyoxylene-polyoxypropylenesorbitan linoleic phthalic ester.

Among the methods of applying lubricants to the fibers of the inventionare those described in U.S. Pat. No. 5,234,702 and 5,372,739 and U.S.application Ser. No. 08/339,619 filed Nov. 15, 1994, and incorporatedherein by reference.

Accordingly, the present invention is also directed to a process forspontaneously transporting an aqueous fluid (which includes water) or analcoholic fluid on the surface thereof. Therefore, a process of thepresent invention can be described as a process for spontaneouslytransporting an aqueous fluid comprising contacting a fiber of thepresent invention with an aqueous fluid. Furthermore, another process ofthe present invention can be described as a process for spontaneouslytransporting an alcoholic fluid comprising contacting a fiber of thepresent invention with an alcoholic fluid. Once the aqueous fluid oralcoholic fluid contacts the fiber, said aqueous fluid or alcoholicfluid will be spontaneously transported. In many applications, it ispreferred to have a portion of the fiber in contact with a source of theaqueous fluid and a different portion of the fiber in contact with asink (the term "sink" will be defined hereinafter).

Fibers of this invention have the uniquely desirable feature ofspontaneously transporting aqueous or alcoholic fluids on theirsurfaces. Since all of these fibers have finite length, e.g., a tow in adiaper which starts and stops at the ends of the diaper or a staplefiber of some specified cut length, the ability to move fluid ceasesonce the fluid reaches the ends of the fibers unless "sinks" for thefluid are provided. Sinks may be, for example, fluff pulp orsuperabsorbant gels, powders or fibers. Ideally, to maximize the utilityof this invention, three key features are desired:

(1) a source of the appropriate fluid to be moved,

(2) the spontaneous surface transport of such fluids which initiates themovement of the fluid and fills the conduits through which the fluidmoves after

the fiber surface becomes "full" of fluid and the spontaneous drivingforces no longer exist, and

(3) a sink or sinks for such fluid which are in intimate contact withthe fiber at one or more locations along the length of each individualfiber.

For example, the practical significance of these three features can beseen in a diaper within the scope of the present invention duringtypical use. The fluid is urine, which and is deposited in significantquantities in a reasonably periodic manner. After the first deposit theurine will be transported spontaneously along each fiber until such timeas the source ceases to emit urine, the urine is absorbed into anadjacent absorbent layer (for which the urine needs to be in contactwith the adjacent absorbent layer for at least about 10 seconds) or theurine contacts a sink. As used herein the term "sink" can be defined asa structure which has a greater affinity for the aqueous fluid than thefiber. Assuming the source of fluid still exists the fiber will act as aconduit to the sink until such time as the source dries up. It is clearthat the locations of the sinks need to be removed from the location ofthe source if significant movement is desired (e.g., the outer area ofthe diaper).

Properly designed capillary structures of round cross-section filamentscan exhibit spontaneous fluid movement. However, the capillary structuredepends on the location of the adjacent filaments and if they happen tomove or be out of position no fluid movement takes place. A uniquefeature of the present invention is that the individual filamentsspontaneously transport aqueous fluids without the need for adjacentfilaments. This allows for many benefits such as for the movement offluids over a much wider surface area. Usually more than one urinationoccurs before a diaper is changed. The second urination (source--at theimpingement zone) will again be transported through the fiber conduitsto appropriate sinks. The spontaneously transportable feature isprobably of less significance the second time than the first urinationbecause the conduits are partially or totally full of fluid. However,without the spontaneously transportable feature relatively little fluidmovement takes place and the source section of the diaper (i.e., theimpingement zone) remains very wet whereas the rest of the diaperremains very dry.

Likewise, the practical significance of these three features can be seenin a catamenial within the scope of the present invention during typicaluse. U.S. Pat. No. 5,356,405 to Thompson et al, issued Oct. 18, 1994 andU.S. Pat. No. 5,334,176 to Buenger et al, issued Aug. 2, 1994 disclosethe use of the fibers of this invention in certain absorbant articles,especially catamenials. Preferably, the fibers of this invention arelocated in a pad-like structure comprising the fibers. The pad is usedin conjunction with an absorbant core, with the core serving as areservoir for fluids which are transferred from the pad comprising thefibers of this invention into the core.

The fibers of the present invention can be comprised of any materialknown in the art capable of having a cross-section of the desiredgeometry and capable of being coated or treated so as to reduce thecontact angle to an acceptable level. Preferred materials for use in thepresent invention are polyesters.

The preferred polyester materials useful in the present invention arepolyesters or copolyesters that are well known in the art and can beprepared using standard techniques, such as polymerizing dicarboxylicacids or esters thereof and glycols. The dicarboxylic acid compoundsused in the production of polyesters and copolyesters are well known tothose skilled in the art and illustratively include terephthalic acid,isophthalic acid, p,p'-diphenyl-dicarboxylic acid,p,p'-dicarboxydiphenylethane, p,p'-dicarboxydiphenylhexane,p,p'-dicarboxydiphenyl ether, p,p'-dicarboxyphenoxyethane, and the like,and the dialkylesters thereof that contain from 1 to about 5 carbonatoms in the alkyl groups thereof.

Suitable aliphatic glycols for the production of polyesters andcopolyesters are the acyclic and alicyclic aliphatic glycols having from2 to 10 carbon atoms, especially those represented by the generalformula HO(CH₂)_(p) OH, wherein p is an integer having a value of from 2to about 10, such as ethylene glycol, trimethylene glycol,tetramethylene glycol, pentamethylene glycol, decamethylene glycol, andthe like.

Other known suitable aliphatic glycols include1,4-cyclohexanedimethanol, 3-ethyl-1,5-pentanediol, 1,4-xylylene,glycol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and the like. One canalso have present a hydroxylcarboxyl compound such as 4,-hydroxybenzoicacid, 4-hydroxyethoxybenzoic acid, or any of the other hydroxylcarboxylcompounds known as useful to those skilled in the art.

It is also known that mixtures of the above dicarboxylic acid compoundsor mixtures of the aliphatic glycols can be used and that a minor amountof the dicarboxylic acid component, generally up to about 10 molepercent, can be replaced by other acids or modifiers such as adipicacid, sebacic acid, or the esters thereof, or with modifiers that impartimproved dyeability to the polymers. In addition one can also includepigments, delusterants or optical brighteners by the known proceduresand in the known amounts.

The most preferred polyester for use in preparing the fibers of thepresent invention is poly(ethylene terephthalate) (PET).

Other materials that can be used to make the fibers of the presentinvention include polyamides such as a nylon, e.g., nylon 66 or nylon 6;polypropylene; polyethylene; and cellulose esters such as cellulosetriacetate or cellulose diacetate.

Other preferred materials useful in preparing the fibers of the presentinvention include binary blends of cellulose esters with aliphaticpolyesters or aliphatic-aromatic copolyesters as well as ternary blendsof cellulose esters with aliphatic polyester/polyacrylates, aliphaticpolyesters/polyvinyl acetates/aliphatic polyesters/polyvinyl alcohol,aliphatic polyesters/polyvinyl chloride, aliphaticpolyesters/polycarbonate, aliphatic polyesters/polyvinylacetate-polyethylene copolymer, aliphatic polyesters/cellulose ethers,aliphatic polyesters/nylon, aliphatic-aromaticcopolyesters/polyacrylates/aliphatic-aromatic copolyesters/polyvinylacetates, aliphatic-aromatic copolyesters/polyvinyl alcohol,aliphatic-aromatic copolyesters/polyvinyl chloride, aliphatic-aromaticcopolyesters/polycarbonate, aliphatic-aromatic copolyesters/polyvinylacetate-polyethylene copolymer, or aliphatic-aromaticcopolyesters/cellulose ethers, and aliphatic-aromatic copolyesters/nylonas more fully described in U.S. Pat. Nos. 5,292,783 and 5,446,079 andU.S. applications Ser. Nos. 08/429,400, 08/428,979, and 08/427,944, allfiled Apr. 26, 1995, incorporated herein by reference. The preferredblends more particularly comprise binary blends of cellulose esters andaliphatic-aromatic copolyesters, cellulose esters and aliphaticpolyesters as well as ternary blends of cellulose esters, aliphaticpolyesters and/or aliphatic-aromatic copolyesters, and polymericcompounds as well as fibers, molded objects, and thin films preparedtherefrom which have one or more of the above or below describeddesirable properties. More specifically, the preferred blends include abinary blend comprising:

I.(A) about 5% to about 98% of a C₁ -C₁₀ ester of cellulose having aDS/AGU of about 1.8 to 3.0 and an inherent viscosity of about 0.2 toabout 3.0 deciliters/gram as measured at a temperature of 25° C. for a0.5 g sample in 100 ml of a 60/40 parts by weight solution ofphenol/tetrachloroethane, and

(B) about 2% to about 95% of a aliphatic-aromatic copolyester having aninherent viscosity of about 0.4 to about 2.0 deciliters/gram as measuredat a temperature of 25° C. for a 0.5 g sample in 100 ml of a 60/40 partsby weight solution of phenol/tetrachloroethane, said percentages beingbased on the weight of component (A) plus component (B); a binary blendcomprising:

II.(A) about 5% to about 98% of a C₁ -C₁₀ ester of cellulose having aDS/AGU of about 1.8 to 2.75 and an inherent viscosity of about 0.2 toabout 3.0 deciliters/gram as measured at a temperature of 25° C. for a0.5 g sample in 100 ml of a 60/40 parts by weight solution ofphenol/tetrachloroethane, and

(B) about 2% to about 95% of a aliphatic polyester having an inherentviscosity of about 0.4 to about 2.0 deciliters/gram as measured at atemperature of 25° C. for a 0.5 g sample in 100 ml of a 60/40 parts byweight solution of phenol/tetrachloroethane, said percentages beingbased on the weight of component (A) plus component (B); ternary blendscomprising:

III. (A) about 4% to about 97% of a C₁ -C₁₀ ester of cellulose having aDS/AGU of about 1.8 to 3.0 and an inherent viscosity of about 0.2 toabout 3.0 deciliters/gram as measured at a temperature of 25° C. for a0.5 g sample in 100 ml of a 60/40 parts by weight solution ofphenol/tetrachloroethane,

(B) about 2% to about 95% of an aliphatic polyester and/or aaliphatic-aromatic copolyester having an inherent viscosity of about 0.4to about 2.0 deciliters/gram as measured at a temperature of 25° C. fora 0.5 g sample in 100 ml of a 60/40 parts by weight solution ofphenol/tetrachloroethane, and

(C) about 1% to about 94% of polymeric compounds having an inherentviscosity of about 0.4 to about 2.0 deciliters/gram as measured at atemperature of 25° C. for a 0.5 g sample in 100 ml of a 60/40 parts byweight solution of phenol/tetrachloroethane, said percentages beingbased on the weight of component (A) plus component (B) plus component(C); blends also comprising:

IV. (A) about 50% to about 99% of a binary blend of (I) or (II) or aternary blend of (III) having an inherent viscosity of about 0.4 toabout 3.0 deciliters/gram as measured at a temperature of 25° C. for a0.5 g sample in 100 ml of a 60/40 parts by weight solution ofphenol/tetrachloroethane,

(B) about 1% to about 50% of biodegradable additives, said percentagesbeing based on the weight of component (A) plus component (B); andblends comprising:

V.(A) about 50% to about 99% of a binary blend of (I) or (II) or aternary blend of (III) having an inherent viscosity of about 0.4 toabout 3.0 deciliters/gram as measured at a temperature of 25° C. for a0.5 g sample in 100 ml of a 60/40 parts by weight solution ofphenol/tetrachloroethane,

(B) about 0.05% to about 2% of immiscible hydrophobic agent, saidpercentages being based on the weight of component (A) plus component(B).

Many of these blends have the advantage of biodegradability orindustrial compostability, so that films or fibers made from the blendsare useful in disposable absorbant articles such as infant diapers,incontinence briefs, sanitary napkins or catamenials, tampons, etc. Theyalso have the advantage of industrial compostability.

A single fiber of the present invention preferably has a denier ofbetween about 3 and about 1,000, more preferred is between about 10 andabout 70.

Fiber shape and fiber/fluid interface variables can be manipulated toincrease fluid transport rate per unit weight of fiber (flux) byaccomplishing the following:

(a) using less polymer by making the fiber cross-sectional area smaller(thinner legs, walls, backbones, etc., which form the channeledstructure);

(b) moderately increasing channel depth-to-width ratio;

(c) changing (increasing or decreasing) channel width to the optimumwidth, and

(d) increasing adhesion tension, α cos θ, at the channel wall by theproper selection of a lubricant for the fiber surface (which resultsprimarily in a decrease in the contact angle at the wall without asignificant lowering of the fluid surface tension at the wall).

The fibers of the present invention preferably have a surface treatmentapplied thereto. Such surface treatment may or may not be critical toobtain the required spontaneous transportability property. The natureand criticality of such surface treatment for any given fiber can bedetermined by a skilled artisan through routine experimentation usingtechniques known in the art and/or disclosed herein. A preferred surfacetreatment is a coating of a hydrophilic lubricant on the surface of thefiber. Such coating is typically uniformly applied at about a level ofat least 0.05 weight percent, with about 0.1 to about 2 weight percentbeing preferred. Preferred hydrophilic lubricants includepolyoxyethylene (23) lauryl ether, polyoxyethylene (20) oleyl ether,polyoxylene-polyoxypropylene-sorbitan linoleic phthalic ester, MileaseT, and a potassium lauryl phosphate based lubricant comprising about 70weight percent poly-(ethylene glycol) 600 monolaurate. Many surfactantsprovide very good wetting of surfaces by lowering fluid surface tensionand decreasing contact angle and thereby yield low adhesion tension atthe surface. Therefore, it is important that the surfactant possess someattraction for the polyester surface (hydrophobic) and also for water(hydrophilic). It is also preferred that the surfactant bind tightly tothe polyester surface and at the same time present high hydrophilicityto the water side of the interface. Another surface treatment is tosubject the fibers to oxygen plasma treatment, as taught in, forexample, Plastics Finishing and Decoration, Chapter 4, Ed. Don Satas,Van Nostrand Reinhold Company (1986).

The novel spinnerets of the present invention must have a specificgeometry in order to produce fibers that will spontaneously transportaqueous fluids.

In FIG. 3, W is between 0.064 millimeters (mm) and 0.12 mm. ##EQU8##

In FIG. 4, W is between 0.064 mm and 0.12 mm; ##EQU9##

In addition, each Leg B can vary in length from 0 to ##EQU10##

and each Leg A can vary in length from 0 to ##EQU11##

In FIG. 5, W is between 0.064 mm and 0.12 mm; ##EQU12##

In FIG. 6, W is between 0.064 mm and 0.12 mm; ##EQU13##

In FIG. 6B, W is between 0.064 mm and 0.12 mm, ##EQU14##

In FIG. 7, the depicted spinneret orifice contains two repeat units ofthe spinneret orifice depicted in FIG. 3. Therefore, the same dimensionsfor FIG. 3 apply to FIG. 7. Likewise, in FIG. 8, the depicted spinneretorifice contains four repeat units of the spinneret orifice depicted inFIG. 3. Therefore, the same dimension for FIG. 3 applies to FIG. 8.

FIG. 33 depicts a preferred "H" shape spinneret orifice of theinvention. In FIG. 33 W₁ is between 60 and 150μ, θ is between 80° and120° S is between 1 and 20, R is between 10 and 100, T is between 10 and300, U is between 1 and 25, and V is between 10 and 100. In FIG. 33 itis more preferred that W₁ is between 65 and 100μ, θ is between 90° and110° S is between 5 and 10, R is between 30 and 75, T is between 30 and80, U is between 1.5 and 2, and V is between 30 and 75.

FIG. 34 depicts a poly(ethylene terephthalate fiber cross-section madefrom the spinneret orifice of FIG. 33. In FIG. 34 W₂ is less than 20μ,W₃ is between 10 and 300μ, W₄ is between 20 and 200μ, W₅ is between 5and 50μ, and W₆ is between 20 and 200μ. In FIG. 34 it is more preferredthat W₂ is less than 10μ, W₃ is between 20 and 100μ, W₄ is between 20and 100μ, and W₅ is between 5 and 20μ.

FIG. 16 illustrates the method for determining the shape factor, X, ofthe fiber cross-section. In FIG. 16, r=37.5 mm, P_(w) =355.1 mm, andD=49.6 mm. Thus, for the fiber cross-section of FIG. 16: ##EQU15##

The fibers of the present invention are preferably incorporated into anabsorbant article in which it is desired to move or transport aqueousfluids. Such absorbant articles include, but are not limited to,diapers, incontinence pads, feminine hygiene articles such as tampons,ink cartridges, wipes, and the like. FIG. 18A shows a schematicrepresentation of the top view of a typical diaper and FIG. 18B shows anexploded side view of a typical diaper along the major axis of thediaper.

The fibers of-the present invention can be in the form of crimped oruncrimped tows or staple fibers comprising a plurality of the fibers ofthe present invention.

An absorbant article of the present invention comprises two or morefibers of the present invention wherein at least part of said fibers arelocated near the center of said absorbant article and at least part ofthe same said fibers are located away from the center of said absorbantarticle; and wherein said fibers are capable of being in contact with anaqueous fluid for about at least 10 seconds near the center of saidabsorbant article; and wherein away from the center of said absorbantarticle one or more sinks are present in said absorbant article that arein contact with said fiber. As used in this context, "near the center"of the absorbant article means the geometric center and the areaconsisting of 50 area % of the total article immediately surroundingsaid geometric center; "away from the center" of the absorbant articlemeans the remaining 50 area % that is not near the center of thearticle. Preferred sinks are fluff pulp, superabsorbant material, andcombinations thereof. It is preferred that said sinks are in contactwith a given fiber near the end of such fiber in the area away from thecenter of the article. As used in this context the term "near the end"of a fiber refers to an actual end of a fiber or the area consisting ofthe end 10% of the length of the fiber.

Another preferred absorbant article of the present invention comprises adiaper or incontinent pad having a major axis and a minor axis and alength in excess of a width which comprises a top sheet, a back sheet,and an absorbant core comprising at least one absorbant layer whereinsaid article further comprises the tow of the present invention. The towmay be crimped or uncrimped.

The tow in said absorbant article can be located in several differentpositions with several different spatial orientations. For example, thetow can be uniformly spread across all or part of the width of thearticle and the fibers of the tow can be substantially parallel to themajor axis of the article and extend from about 1/2 to substantially thelength of the article (see FIG. 23B).

Alternatively, the fibers of the tow can be substantially parallel tothe major axis of the diaper and extend substantially the length of thediaper (see FIG. 23A).

By use of a tow of the fibers of the invention in an absorbant articlesuch as a diaper, urine can be transported to a larger surface area onthe diaper. Thus, the amount of superabsorbant material required in thediaper can be reduced and the diaper surface will be drier.

By utilizing the fibers of the present invention in a diaperconstruction, it is preferred that at least one of the followingbenefits be realized.

(i) The effective surface area of the diaper utilized for urine/aqueousfluid movement will increase by 5% to 30%.

(ii) The amount of superabsorbant material utilized in the diaper willreduce by 2% to 25%.

(iii) The diaper will be thinner by about 2% to 15%.

(iv) The strikethrough (seconds)/rewet (grams) responses as measured bythe strikethrough/rewet test described in U.S. Pat. No. 4,324,247 areimproved with the strike-through being reduced from about 2 to about 50%and the rewet being reduced from about 2 to about 70% when compared toequivalent structures without the fibers (tow) of this invention beingpresent. This results in the interface between the diaper and the wearerremaining drier.

The fibers of the tow can be located in the absorbant article at anyplace which will result in an overall beneficial effect. For example,the fibers can be located between the top sheet and the absorbant core,incorporated into the absorbant core, between the absorbant core and theback sheet, or multiple combinations of the above.

The top sheet of the absorbant article of the present invention can bemade of any material known in the art for such use. Such materialsinclude, but are not limited to, polypropylene, polyethylene,polyethylene terephthalate, cellulose or rayon; preferred ispolypropylene. The top sheet is the sheet which is designed to be incontact with the body during typical end uses. Such a top sheet isalternatively referred to in the art as a "facing sheet," and it istypically comprised of a web of short and/or long fibers.

The back sheet of the absorbant article of the present invention can bemade of any material known in the art for such use. Such materialsinclude, but are not limited to, polyethylene, a polyester, orpolypropylene; preferred is polyethylene. The back sheet is typicallyimpervious to body fluids such as urine.

The absorbant core of the absorbant article of the present inventionpreferably comprises fluff pulp and, optionally, superabsorbant powder.Fluff pulp is used extensively in the art. Fluff pulp is a batt formedof loosely compacted short cellulose fibers, such as wood pulp fibers,or cotton linters, or mixtures thereof, which are primarily heldtogether by interfiber bonds usually requiring no added adhesivealthough thermoplastic binder(s) may also be used. This batt is a lowdensity coherent web of loosely compacted fibers preferably comminutedwood pulp fibers. Examples of absorbant powder are polyacrylates,acrylic acid based polymers, saponified starch, and polyacrylonitrilegraft copolymers.

Other preferred embodiments of the absorbant article of the presentinvention include articles wherein the fibers of the tow are tightlycompacted in the impingement zone such that the fibers are substantiallyin contact with each other, and toward each end of the length of thearticle the fibers of the tow flare and are substantially not in contactwith each other (see FIG. 24). In addition, the tow can have from onehalf to ten turns of twist in the impingement zone. The terms"impingement zone", "impinging area", and like terms refer to that areaor zone where body fluid first contacts or impinges upon the absorbantarticle during its intended use. The impingement zone may be near thecenter of the absorbant article, away from the center, or overlappingboth areas.

It is also contemplated that the fibers of the present invention can bein the form of staple fiber which may or may not be crimped. When in theform of staple fiber, a preferred absorbant article of the presentinvention comprises a diaper or incontinent pad having a major axis anda minor axis and a length in excess of a width comprising a top sheet, aback sheet, and an absorbant core comprising at least one absorbantlayer wherein said core comprises an intimate blend of the staple fiberof the present invention (see FIG. 22).

Another preferred embodiment of the absorbant article of the presentinvention is wherein the an article containing up to three tows of theinvention wherein the major axis of each tow lies between ±30° aroundthe major axis of the article and wherein the tows lie either justbeneath the top sheet, lie intimately mixed with the absorbant core orlie adjacent to the back sheet (see FIG. 25).

Another preferred embodiment of the absorbant article of the presentinvention is a two piece diaper wherein one piece contains tow of theinvention and receives the impinging fluid during the diaper's intendeduse and is reusable, and wherein the second piece is a fluid storageelement and is replaceable.

The absorbant article of this invention can optionally contain a tissueor low density spacer layer which is adjacent to the top sheet betweenthe top sheet and absorbant core. In such case the tow preferably liesbetween the absorbant core and said tissue or density spacer.

In still another preferred embodiment of the absorbant article of thepresent invention the fibers of the tow are in intimate contact withpart of the absorbant core located away from the impingement zone.

Other absorbant articles contemplated by the present invention (whichmay or may not have a specific impingement zone) in which the fibers ofthe present invention can be beneficial include, but are not limited to,a sweat absorbing headband or wristband, a surgical sponge, a wounddressing, a sweat absorbing insole for footwear, a general purposewiping article, a fabric softener strip for use in clothes dryers, awound drain or a surgical drain, a towel, a geotextile, athleticclothing such as athletic socks and jogging suits, a cosmeticapplicator, a furniture polish applicator, a pap smear sampler, a throatculture sampler, a blood-analyzer test element, household and industrialdeodorizers, humidifier fabric, moist filter media, orthopaedic castliners, wipes for medical applications (e.g., containing an alcoholicfluid for use on the surface of skin) and the like.

Ink cartridges are typically made with tows of cellulose ester fibersand polyester fibers. Important criteria for ink cartridges are (i) inkholding capacity and (ii) effective utilization of the ink reservoir.The art of making ink cartridges is described in U.S. Pat. Nos.4,104,781, 4,286,005, and 3,715,254. The use of fiber bundles made fromfibers of the present invention in these ink cartridges offersignificant advantages of increased ink holding capacity and/oreffective utilization of the ink reservoir due to the nature of thefiber cross-sections and the spontaneous surface transportable nature ofthe single fibers of the present invention.

In the geotextile field, one of the important functions of thegeotextile material is to transport rain water and other aqueous fluidsfrom unwanted regions of the land to distant areas. It is believed thatdue to the spontaneous surface transportable nature of the fibers of thepresent invention, articles made from these fibers will enhance intransporting aqueous fluids from one region to another area ingeotextile applications.

In active sports and outdoor activities, it is important that the humanbody remain relatively dry for comfort. Generally, human sweat orperspiration causes a feeling of being "wet". One of the importantfunctions of garments and other articles worn next to skin is then torapidly transport the "sweat" or "perspiration" from the skin to thegarment or article worn next to the skin. Furthermore, it is importantthat such garments and articles should not absorb the bulk of this"sweat"; otherwise, it will take a long time to remove or dry theaqueous fluids from such garments and articles. For example, garments orsuch articles made of cotton or cellulosic fibers have a very high waterabsorption capacity (7-10%) and thus may not be highly desirable in suchapplications. However, garments or such articles worn next to skin madefrom fibers of the present invention and/or those in conjunction withblends of other fiber types may be very desirable. The spontaneoussurface transportable nature of the fibers of the present invention canlead to rapidly removing the "sweat" or "perspiration" from the humanbody and thereby keeping the body relatively dry. Thus, a sweatabsorbing headband or wristband, an insole for footwear, a towel,athletic socks, jogging suit, etc. made from fibers of the presentinvention can be highly desirable.

The fibers of the present invention can be prepared by techniques knownin the art and/or disclosed herein using a novel spinneret of thepresent invention or other spinneret that will result in a fibercross-section of the appropriate geometry and properties.

In general, a process of the present invention can be described as aprocess for preparing a fiber of the present invention which comprisesheating a material capable of forming a fiber at or above its meltingpoint followed by extruding said heated material through at least onespinneret having at least one orifice capable of forming the desiredfiber. The fiber may be drafted and/or thermally stabilized. The fiberthus formed may then optionally be treated with a surface treatment suchas a hydrophilic coating or plasma treatment as described hereinbefore.

The absorbant articles of the present invention can be made by use oftechniques known in the art, for example in U.S. Pat. Nos. 4,573,986;3,938,522; 4,102,340; 4,044,768; 4,282,874; 4,285,342; 4,333,463;4,731,066; 4,681,577; 4,685,914; and 4,654,040; and/or by techniquesdisclosed herein. The tow of the present invention can be incorporatedinto the absorbant article at any location which will improve fluidmovement so as to better utilize the absorbant materials of the article.

Spunbonded structures, well known in the art, can also be made fromfilament strands of the present invention. Care must be exercised in thecalendaring step so as not to damage the cross-section of the fibers andthereby inhibit the spontaneous surface transport.

Continuous filament yarns of typical textile deniers and filament countscan also be made using the present invention. The yarns are useful inproviding scrim fabrics which will spontaneously surface transportaqueous fluids.

The following examples are to illustrate the invention but should not beinterpreted as a limitation thereon.

EXAMPLES Example 1 (Base Fiber Preparation)

Poly(ethylene terephthalate) (PET) polymer of 0.6 I.V. was used in thisexample. I.V. is the inherent viscosity as measured at 25° C. at apolymer concentration of 0.50 g/100 milliliters (mL) in a suitablesolvent such as a mixture of 60% phenol and 40% tetrachloroethane byweight. The polymer was dried to a moisture level of ≦0.003 weightpercent in a Patterson Conaform dryer at 120° C. for a period of 8hours. The polymer was extruded at 283° C. through an Egan extruder,1.5-inch diameter, with a length to diameter ratio of 28:1. The fiberwas extruded through an eight orifice spinneret wherein each orifice wasas shown in FIG. 3, wherein W was 0,084 mm, X₂ was 4W, X₄ was 2W, X₆ was6W, X₈ was 6W, X₁₀ was 7W, X₁₂ was 9W, X₁₄ was 10W, X₁₆ was 11W, X₁₈ was6W, θ₂ was 0°, θ₄ is 45°, θ₆ is 30°, and θ₈ was 45°. The polymerthroughput was about 7 pounds (lb)/hour. The air quench system has across-flow configuration. The quench air velocity at the top of thescreen was an average of 294 feet (ft)/minute. At a distance of about 7inches from the top of the screen the average velocity of the quench airwas about 285 ft/minute, and at a distance of about 14 inches from thetop of the screen the average quench air velocity was about 279ft/minute. At about 21 inches from the top of the air screen the averageair velocity was about 340 ft/minute. The rest of the screen wasblocked. Spinning lubricant was applied via ceramic kiss rolls. Thelubricant had a general composition as follows: it was a potassiumlauryl phosphate (PLP) based lubricant having poly(ethylene glycol) 600monolaurate (70% by weight) and polyoxyethylene (5) potassium laurylphosphate (30% by weight). An emulsion of the above lubricant with water(90%) was used as the spinning lubricant. The lubricant level on thefiber samples was about 1.5%. Fibers of 20 dpf (denier per filament)were wound at 3,000 meters per minute (MPM) on a Barmag SW4SL winder. Aphotomicrograph of a cross-section of this fiber is shown in FIG. 9(150×magnification). The single fiber was tested for spontaneous surfacetransportation of an aqueous solution which was aqueous Syltint PolyRed® (obtained from Milliken Chemicals) which is 80 weight % water and20 weight % red colorant. The single fiber of 20 dpf spontaneouslysurface transported the above aqueous solution. The following denier perfilament PET fibers were also made at different speeds as shown in TableI below:

                  TABLE I                                                         ______________________________________                                                      Spin Speed                                                      dpf           (MPM)     Winder                                                ______________________________________                                        20            3,000     Barmag                                                40            1,500     Leesona                                               60            1,000     Leesona                                               120           500       Leesona                                               240           225       Leesona                                               400           150       Leesona                                               ______________________________________                                    

All the single fibers of above PET fiber with the dpf of 20, 40, 60,120, 240, and 400 spontaneously surface transported the aqueous solutionof Syltint Poly Red® liquid. The value of the "X" parameter (as definedhereinbefore) for these fibers was about 1.7. PET film of 0.02 inchthickness was compression molded from the same polymer as that used formaking the above fiber. The contact angle of distilled water on theabove film was measured in air with a contact angle goniometer. Thecontact angle was 71.7° Another sample of the same film as above wassprayed with the same lubricant as used for making the fiber in thisexample at about 1.5% level. The contact angle of distilled water on thePET film sprayed with the lubricant was about 7° Thus, the factor (1-Xcos θ) in this case was (1-1.7(cos 7°))=-0.69, which is less than zero.

Example 2 (Base Fiber Preparation)

Polyhexamethylene adipamide (nylon 66) was obtained from Du Pont (Zytel®42). The polymer was extruded at 279° C. A spinneret as shown in FIG. 3was used to form 46 dpf fiber at 255 meters/minute speed. The specificdimensions of the spinneret orifices were the same as described inExample 1 except that θ₂ was 30° instead of 0°. The quenching conditionswere the same as those for obtaining PET fiber as in Example 1. Aphotomicrograph of the fiber cross-section is shown in FIG. 11(150×magnification). The lubricant level on the fiber was about 1.8% byweight. The same lubricant as used in the PET fiber was used (Example1). This Nylon 66 fiber spontaneously transported the aqueous SyltintPoly Red® solution on the fiber surface. The value of the "X" parameterfor this fiber was about 1.9. Nylon 66 film of 0.02 inch thickness wascompression molded from the same polymer as that used for making thefiber of Example 2. The contact angle of distilled water on the abovefilm was measured in air with a contact angle goniometer. The contactangle was 64°. Another sample of the same film as above was sprayed withthe same lubricant as used for making the fiber in this example at aboutthe 1.8% level. The contact angle of distilled water on the nylon 66film sprayed with the lubricant was about 2°. Thus, the factor (1-X cosθ) in this case was (1-1.9 (cos 2°))=-0.9, which is less than zero.

Example 3 (Base Fiber Preparation)

Polypropylene polymer was obtained from Shell Company (Grade 5C14). Itwas extruded at 279° C. A spinneret as shown in FIG. 3 was used to form51 dpf fiber at 2,000 MPM speed. The specific dimensions of thespinneret orifices were the same as in Example 2. The quenchingconditions were the same as those for obtaining PET fiber. Aphotomicrograph of the fiber cross-section is shown in FIG. 10(375×magnification). The lubricant level on the fiber was 2.6%. The samelubricant as used in PET fiber was used (Example 1). The polypropylenefiber spontaneously transported the aqueous Syltint Poly Red® solutionon the fiber surface. This spontaneously transportable phenomenon alongthe fiber surface was also observed for a 10 dpf, single polypropylenefiber. The value of the "X" parameter for this fiber was about 2.2.Polypropylene film of 0.02 inch thickness was compression molded fromthe same polymer as that used for making the above fiber of Example 3.The contact angle of distilled water on the above film was measured inair with a contact angle goniometer. The contact angle was about 110°.Another sample of the same film as above was sprayed with the samelubricant as used for making the fiber in this example at about the 2.6%level. The contact angle of distilled water on the polypropylene filmsprayed with the lubricant was 12°. Thus, the factor (1-X cos θ) in thiscase was -1.1, which is less than zero.

Example 4 (Base Fiber Preparation)

Cellulose acetate (Eastman Grade CA 398-30, Class I) was blended withPEG 400 polymer and small quantities of antioxidant and thermalstabilizer. The blend was melt extruded at 270° C. A spinneret as shownin FIG. 3 was used to form 115 dpf fiber at 540 meters/minute speed. Thespecific dimensions of the spinneret orifices were the same as inExample 2. No forced quench air was used. The lubricant level on thefiber was 1.6%. The same lubricant as used in the PET fibers (Example 1)was used. The cellulose acetate fiber spontaneously transported theaqueous Syltint Poly Red® solution on the fiber surface. The value ofthe "X" parameter for this fiber was about 1.8.

Example 5 (Comparative)

PET fiber of Example 1 was made without any spinning lubricant at 20dpf. A single fiber did not spontaneously transport the aqueous SyltintPoly Red® solution along the fiber surface.

Example 6 (Comparative)

PET fiber of circular cross-section was made. The denier per filament ofthe fiber was 20. It had about 1.5% of the lubricant used in Example 1.A single fiber did not spontaneously transport the aqueous Syltint PolyRed® solution along the fiber surface.

Example 7 (Base Fiber Preparation)

Poly(ethylene terephthalate) (PET) fiber of Example 5 (without anyspinning lubricant) was treated with oxygen plasma for 30 seconds. Model"Plasmod" oxygen plasma equipment was used. Exciter power was providedby the RF generator operating at 13.56 MHz frequency. The plasmatreatment was conducted at a constant level of 50 watts power. Theoxygen plasma treated fiber spontaneously transported the aqueousSyltint Poly Red® solution along the fiber. This fiber was tested againafter washing five times and after 3 days and the spontaneouslytransportable behavior with the above aqueous solution was stillobserved. In order to determine the reduction in contact angle after theplasma treatment, a PET film of the same material as that of the fiberwas subjected to the oxygen plasma treatment under the same conditionsas those used for the fiber sample. The average contact angle of theoxygen plasma treated film with distilled water in air was observed tobe 26° as measured by a contact angle goniometer. The correspondingcontact angle for the control PET film (not exposed to the oxygenplasma) was 70°. The significant reduction in contact angle uponsubjecting the untreated PET fiber to the oxygen plasma treatmentrendered it to be spontaneously surface transportable for aqueoussolutions.

Example 8 (Base Fiber Preparation)

Poly(ethylene terephthalate) (PET) polymer of 0.6 IV was used in thisexample. It was extruded through a spinneret having eight orifices asshown in FIG. 4 wherein W was 0.084 mm, X₂₀ was 17W, X₂₂ was 3W, X₂₄ was4W, X₂₆ was 60W, X₂₈ was 17W, X₃₀ was 2W, X₃₂ was 72W, θ₁₀ was 45° Leg Bwas 30W, and Leg A was 26W. The rest of the processing conditions werethe same as those described in Example 1. A 100 dpf fiber was spun at600 MPM. A sketch of the cross-section of the fiber is shown in FIG. 12.The lubricant level on the fiber was about 1%. The same lubricant asused in Example 1 was used. The above fiber spontaneously transportedthe aqueous Syltint Poly Red® solution along the fiber surface. Thevalue of the "X" parameter for this fiber was 1.5.

Example 9 (Base Fiber Preparation)

Poly(ethylene terephthalate) polymer of 0.6 IV was used in this example.It was extruded through a spinneret having eight orifices as shown inFIG. 5 wherein W was 0.10 mm, X₃₄ was 2W, X₃₆ was 58W, X₃₈ was 24W, θ₁₂is 20°, θ₁₄ was 28° and n was 6 The rest of the extruding and spinningconditions were the same as those described in Example 1. Aphotomicrograph of the fiber cross-section is shown in FIG. 13(585×magnification). A 20 dpf fiber was spun at 3000 MPM. The lubricantlevel on the fiber was about 1.7%. The same lubricant as used in Example1 was used. The above fiber spontaneously transported the aqueousSyltint Poly Red® solution along the fiber surface. The value of the "X"parameter for this fiber was about 2.4.

Example 10 (Base Fiber Preparation)

Poly(ethylene terephthalate) (PET) polymer of about 0.6 IV was used inthis example. The polymer was extruded through a spinneret having fourorifices as shown in FIG. 7 wherein the dimensions of the orifices wererepeats of the dimensions described in Example 2. The rest of theprocessing conditions were the same as those described in Example 1unless otherwise stated. A 200 dpf fiber was spun at 600 MPM. Thepolymer throughput was about 7 lbs/hr. An optical photomicrograph of thefiber is shown in FIG. 14 (150×magnification). The lubricant level onthe fiber was 2.0%. The same lubricant as used in Example 1 was used.The above fiber spontaneously transported the aqueous Syltint Poly Red®solution along the fiber surface. The value of the "X" parameter forthis fiber was about 2.2.

Example 11 (Base Fiber Preparation)

Poly(ethylene terephthalate) (PET) polymer of 0.6 IV was used in thisexample. The polymer was extruded through a spinneret having twoorifices as shown in FIG. 8 wherein the dimensions of the orifices wererepeats of the dimensions described in Example 2. The rest of theprocessing conditions were the same as those described in Example 1. A364 dpf fiber was spun MP 600 MPM. The cross-section of the fiber isshown in FIG. 15 (150×magnification). The lubricant level on the fiberwas about 2.7%. The same lubricant as used in Example 1 was used. Theabove fiber spontaneously transported the aqueous Syltint Poly Red®solution along the fiber surface. The value of the "X" parameter forthis fiber was 2.1.

Example 12 (Base Fiber Preparation)

Poly(ethylene terephthalate) (PET) polymer of 0.6 IV was used in thisexample. It was extruded through a spinneret having eight orifices asshown in FIG. 6 wherein W was 0.10 mm, X₄₂ was 6W, X₄₄ was 11W, X₄₆ was11W, X₄₈ was 24W, X₅₀ was 38W, X₅₂ was 3W, X₅₄ was 6W, X₅₆ was 11W, X₅₈was 7W, X₆₀ was 17W, X₆₂ was 28W, X₆₄ was 24W, X₆₆ was 17W, X₆₈ was 2W,θ₁₆ was 45°, θ₁₈ was 45°, and θ₂₀ was 45°. The rest of the processingconditions were the same as those described in Example 1. A 100 dpffiber was spun at 600 MPM. The cross-section of the fiber is shown inFIG. 17. The lubricant level on the fiber was about 1%. The samelubricant as used in Example 1 was used. The above fiber spontaneouslytransported the aqueous Syltint Poly Red® solution along the fibersurface. The value of the "X" parameter for this fiber was 1.8.

Example 13 (Base Fiber Preparation)

PET polymer of 0.6 I.V. was used in this example. It was extrudedthrough a spinneret having 8 orifices as shown in FIG. 6B wherein W was0.10 mm, X₇₂ was 8W, X₇₄ was 8W, X₇₆ was 12W, X₇₈ was 8W, X₈₀ was 24W,X₈₂ was 18W, X₈₄ was 8W, X₈₆ was 16W, X₈₈ was 24W, X₉₀ was 18W, X₉₂ was2W, θ₂₂ was 135°, θ₂₄ was 90°, θ₂₆ was 45°, θ₂₈ was 45°, θ₃₀ was 45°,θ₃₂ was 45°, θ₃₄ was 45°, θ₃₆ was 45°, and θ₃₈ was 45°. A 20 dpf fiberwas spun at 3,000 m/min. The rest of the processing conditions are thesame as those used in Example 1. The lubricant level on the fiber wasabout 1%. The cross-section of the fiber is shown in FIG. 17B. Thisfiber spontaneously transported the aqueous Syltint Poly Red® solutionalong the fiber surface. The "X" value for this fiber was about 2.1.

Example 14 (Examples of the Invention)

A disposable absorbant article is prepared comprising (a) a liquidimpervious backing sheet made of polyethylene, (b) a relativelyhydrophobic, liquid pervious top sheet made of polypropylene, (c) alayered absorbant core positioned between said backing sheet and saidtop sheet, and (d) tow or fibers of the present invention. The cover orfacing provided on the absorbant structure is a non-woven fabric havinga high degree of moisture permeability. For example, the fabric may bepolyester, polyethylene, polypropylene, nylon, rayon, or the like.Preferably, the fabric used for the cover is a lightweight fabric in therange of 0.3 to 5.0 oz./square yard and with a density less than 0.3g/cc. The most suitable fabrics have unusually high elongation,softness, and drape characteristics. Though the cover is moisturepermeable, it is preferably of the type which after permeation of themoisture prevents strike-back of the body fluid when the absorbantstructure is approaching saturation. The body of the cellulosic fibrousbatt (fluff pulp) is substantially more wettable than the cover andtends to draw liquid away from the facing layer. The cellulosic batt maybe wrapped in a tissue. It may not be necessary to have a tissuewrapping the cellulosic batt. However if the cellulosic batt is quitethick, such as an inch or more, it may be desirable to provide a tissuewrap to assist with maintenance of the desired shape of the absorbantstructure. The cellulosic batt also contains a water-swellable,water-insoluble absorbant composition. The superabsorbant particles aregenerally in the form of a dry solid water-swellable, water-insolubleabsorbant composition such as an ionic complex of a water-solubleanionic polyelectrolyte and a polyvalent metal cation. Typicalsuperabsorbant compositions are illustrated in U.S. Pat. No. 4,090,013to S. H. Ganslaw et al. and U.S. Pat. No. 4,043,952 to S. H. Ganslaw etal. The superabsorbant material may be in the form of individualparticles or strips of film to which the superabsorbant material isadhered to other known superabsorbant compositions. The superabsorbantmaterial may be affixed to the base of the super-absorbant reservoir ormay simply lie independently within the reservoir. The fibers of thepresent invention may be placed in a tow form or fiber bundleimmediately below the top sheet as shown in FIG. 19. By using the tow ofthe fibers of the present invention, the body fluid (e.g., urine) willbe spread farther along the absorbant article (thus improving thestrikethrough and rewet properties), thereby more effectively utilizingthe available absorbant area and superabsorbant material and resultingin a drier skin-absorbant article interface.

Example 15 (Example of the Invention)

The components of the disposable absorbant article are the same as inExample 14. However, in this case the fibers of the present inventionare placed in a tow form within the cellulosic batt (absorbant core) asshown in FIG. 21. By using the tow of the fibers of the presentinvention, the body fluid (e.g., urine) will be spread farther along theabsorbant article (thus improving the strikethrough and rewetproperties), thereby more effectively utilizing the available absorbantarea and superabsorbant material and resulting in a drier skin-absorbantarticle interface.

Example 16 (Example of the Invention)

The components of the disposable absorbant article are the same as inExample 14. However, in this case the fibers of the present inventionare placed in the tow form immediately below the cellulosic batt(absorbant core) as shown in FIG. 20. By using the tow of the fibers ofthe present invention, the body fluid (e.g., urine) will be spreadfarther along the absorbant article (thus improving the strikethroughand rewet properties), thereby more effectively utilizing the availableabsorbant area and superabsorbant material and resulting in a drierskin-absorbant article interface.

Example 17 (Example of the Invention)

The components of the disposable absorbant article are the same as inExample 14. However, in this case the fibers of the present inventionare placed in the layer containing the cellulosic batt (absorbant core).There is an intimate blend of the staple fiber of the present inventionand fluff pulp (hydrophilic cellulosic fiber). The fibers of the presentinvention are in cut, staple form 0.25 inch to 6 inches in length (seeFIG. 22). By using the tow of the fibers of the present invention, thebody fluid (e.g., urine) will be spread farther along the absorbantarticle (thus improving the strikethrough and rewet properties), therebymore effectively utilizing the available absorbant area andsuperabsorbant material and resulting in a drier skin-absorbant articleinterface.

Example 18 (Example of the Invention)

The components of the disposable absorbant article are the same as inExample 14. However, in this case the fibers of the present inventionare placed in the tow form above and below the cellulosic batt(absorbant core) as shown in FIG. 26. By using the tow of the fibers ofthe present invention, the body fluid (e.g., urine) will be spreadfarther along the absorbant article (thus improving the strikethroughand rewet properties), thereby more effectively utilizing the availableabsorbant area and superabsorbant material and resulting in a drierskin-absorbant article interface.

Example 19 (Example of the Invention)

The components of the disposable absorbant article are the same as inExample 14. However, in this case the fibers of the present inventionare in the tow form and tightly compacted in the impingement zone (thetow may also be twisted in the impingement zone) such that the fibersare substantially in contact with each other (thereby promoting rapidmovement of urine or other bodily fluids along the fiber axis due to thecombined action of the spontaneous surface transportable nature of thesesingle fibers and the capillary flow in the void space between thefibers), and toward each end of the length of the article the fibers ofthe tow flare and are substantially not in contact with each other. Onepossible arrangement is shown in FIG. 24. This arrangement will allowrapid movement of urine from the impingement zone to the outer areas ofthe diaper. By using the tow of the fibers of the present invention, thebody fluid (e.g., urine) will be spread farther along the absorbantarticle (thus improving the strikethrough and rewet properties), therebymore effectively utilizing the available absorbant area andsuperabsorbant material and resulting in a drier skin-absorbant articleinterface.

Example 20 (Example of the Invention)

Tows of this invention are very useful for making ink reservoircartridges for writing instruments which utilize aqueous based inks.96/8 d/f PET yarns were made using the conditions of Example 1 exceptthe lubricant level was 3.4%. These yarns were plied, drafted 1.5×,thermally stabilized, crimped and pulled into cylindrical cartridges(0.70 cm in diameter) such that the density in the cartridges rangedfrom about 0.10 g/cc to about 0.25 g/cc. Appropriate round cross-sectionPET control was made at 8 dpf with 1% of the lubricant used in Example1, crimped and pulled into the same size cylindrical cartridges suchthat the densities ranged from about 0.10 g/cc to about 0.25 g/cc. Thesecylindrical cartridges were cut to lengths of 7.95 cm and all of thetesting was done using Sheaffer Skript® writing fluid, washable black#632.

FIG. 27 shows the ink holding capacity versus cartridge density forcartridges made from fibers of the present invention and round fibercontrols. This test basically involved dripping ink into the cartridgesof known weight held in a vertical position and determining the amountof ink the cartridge held when it began to drip from the bottom of thecartridge. This weight in grams was called the ink holding capacity ofthe cartridge being tested. The improvement ranged from about 13% to 26%over the range of densities tested.

FIG. 28 shows the percent ink remaining versus cartridge density forcartridges made from PET fibers of the present invention and round PETfiber controls. Percent ink remaining was defined as

    ink remaining in the cartridge after dewicking (g)/ink holding capacity (g)×100

where the ink remaining in the cartridge after dewicking was determinedby weighing the cartridge, filling it with ink (ink holding capacity),weighing the cartridge plus ink, contacting the bottom of the cartridgewith Type F2 Buckeye Filter paper and dewicking until such time as noink left the cartridge, weighing the cartridge plus ink remaining andfinally subtracting the weight of the cartridge to determine the weightin grams of the ink remaining in the cartridge. Notice the clearlysuperior behavior of the cartridge containing fibers of the presentinvention.

FIG. 29 shows useable ink versus cartridge density for cartridges madefrom fibers of the present invention and round fiber controls. This testinvolved dripping ink into the cartridge of known weight such that itsink holding capacity was equaled, contacting the bottom of the cartridgewith Type F2 Buckeye Filter paper and dewicking until such time as noink left the cartridge, weighing the cartridge plus unavailable ink andsubtracting the weight of the unavailable ink (g) from the ink holdingcapacity (g) to determine the useable ink in grams. The improvementranged from about 15% to about 30% over the range of densities tested.

FIG. 30 shows the ratio of useable ink to fiber weight versus cartridgedensity for cartridges made from fibers of the present invention andround fiber controls. Notice the significant improvement of thecartridges made from fibers of the present invention.

Example 21--Uphill Flux Test Scope and Significance

This method is used to determine the fluid transport rate of capillarytransport materials from a reservoir of synthetic urine fluid along anincline to an absorbant. This computer monitored version of the methodautomatically measures the fluid uptake of the test materials andprovided a profile of the weight gain of the transport and absorbantstorage materials with time. The spontaneous movement of the fluid upthe incline and through the transport material is a quantitative measureof the surface and capillary forces acting on the fluid in opposition togravity. Uphill transport testing provides a means of comparing ratedifferences due to the type and size of capillary transport materials aswell as surface treatments and geometries. The test can also be used toevaluate the effects of test fluid surface tension as well as differentabsorbant materials. Finally, the test can be modified to simulatein-use conditions such as removing the reservoir and replacing it laterto simulate multiple urine additions.

Summary of Method

The uphill transport test is used to determine the fluid transport rateof capillary transport materials from a reservoir of synthetic urinetest fluid along a 20 cm long ramp to an absorbant on an attachedplatform at 10 cm height. Once the prepared specimen is mounted on theplatform/incline, the operator initiates the test according to theinstructions given by the computer program by placing the lower end ofthe transport material in the reservoir of fluid. The test continues for90 minutes or until terminated by the operator.

Definitions

The terms employed in this method are commonly used in normal laboratorypractice and require no special comment.

Safety Precautions

Normal safety precautions and safe handling practices should beobserved.

Sources of Error

Fluid transport is very surface and geometry dependent. Surfacecontamination should be avoided and sample handling should be minimized.

Condition all fiber and fabric samples, including the storage orabsorbant material, at least overnight in the laboratory before testingso that the moisture content is controlled by the relative humidity inthe laboratory.

The balance is very sensitive to fluid movement in the two reservoirs.Because the fluid transported by the test specimen is the measuredresponse of the test, an accurate tare weight of the fluid before thetest is started is essential. The computer does not take this tareweight reading until the specimen to be tested has been identified tothe computer and the label is accepted as correct by the operator.Therefore, prior to this time in the program, adjustments in thespecimen or test apparatus can be made without affecting the results.All adjustments must be made prior to this point in the testingprocedure.

Apparatus

A schematic representation of the apparatus used is in FIG. 39.

Reagents and Materials

SYN-URINE test fluid from Jayco

Pharmaceuticals (dyed with food coloring to aid observation)

Transport material of choice, in most cases this will be a sheet of PETfilaments

Absorbant or storage material, such as Bounty® towels or diaper coresections

Calibration and Standardization

Sample Preparation

Weigh a quantity of transport material precut to 40 cm length. Pull outa 20 cm length of Saran Wrap from its 12-inch wide dispenser box. The111/2-inch wide roll of wrap is just the right size to place around thetransport material from the bottom or back side to the top side with theends of the wrap just meeting on the top for minimum overlap (1/8-1/4inch). Wrap loosely with Saran Wrap with about 5 cm of transportmaterial sticking out from the end to be placed in the reservoir andwith 15 cm sticking out from the end to be placed in the absorbant. Theresulting area of transport material covered with wrap will be 20 cmlength by 51/2 inch width. This covering minimizes evaporation from thetransport material between the reservoir and the absorbant. Cut theabsorbant material of choice to 6 inch×6 inch size.

Mount the covered transport material on the ramp with its previouslyassembled absorbant or assemble the transport material/absorbant layerson the ramp. Be sure the filled reservoir has been previously coveredwith stiff paper or cardboard so the 5 cm tail of the transport materialwill not enter the fluid until the computer has been set up and is readyto start the data collection process. Once the absorbant is in place onthe horizontal part of the ramp, apply a load weight over the absorbant(usually 0.1 psi).

Procedure

After turning on the computer, note the test menu and the C>prompt. Type"date" and enter the current date Return!. Type "UP" to start the testprogram. Follow the instructions on the computer screen. Stop after youhave labeled the sample to be tested. Accepting the labeling as correctwill cause the computer to read the balance, and this must not occuruntil the balance has stabilized with the test specimen and any weightscompletely in place.

The test is started once the balance is stable by removing the reservoircover and allowing the transport material to enter the transport fluid.Press Return! when this occurs to start the computer program thatcollects the weight data.

The computer program is designed so that two transport processes arefollowed. The first one is when the fluid moves up the incline of theramp until the fluid front just reaches the absorbant at the top of theincline. This is the "induction" process. The computer must know whenthe fluid reaches the absorbant material. Pressing the F5 key tells thecomputer to calculate the induction process and to begin collecting datafor the "transport" process that occurs as the fluid moves in theabsorbant material at the top of the ramp.

At the end of the test (90 minutes total or sooner if the test isterminated by the operator) enter the weight of the transport materialas requested by the computer. The computer calculates the appropriatetimes and flux values and puts the results on the printer. The computeris programmed in any conventional way to carry out these calculations.The specific program used in the Examples of this invention isexemplified in Example 24.

Example 22--Measurement of Adhesion Tension

This describes the measurement of adhesion tension between a liquid andthe surface of a polymer film. The adhesion tension at asolid-liquid-air interface is defined as the force per unit length ofinterface exerted on the solid surface in the plane of the surface andnormal to the interface. The apparatus used here consists of a Cahn 2000Recording Microbalance with a resolution of about 0.1 μg and a RameHarte Vertical Platform Assembly, which moves vertically at uniformspeeds down to a fraction of a micron per second.

About 50 ml of the liquid of interest is placed beneath the microbalanceon the platform in a cylindrical container with a diameter of about 5cm. A rectangular sample approximately 1 cm by 2 cm is cut from thepolymer film with shears or with a razor knife depending on thethickness of the film. The sample should be flat and of uniformthickness and must be relatively rigid. It is important that the edgesbe straight, square and sharp and that the surface be free offingerprints or other contamination. The sample is suspended from themicrobalance by means of a small hook fastened with glue or tape to thecenter of one of the short edges. The hook should be bent gently so thatthe sample hangs vertically with its bottom edge parallel to the liquidsurface, and the liquid container should be centered beneath it. Theplatform is raised by means of a coarse motor until the liquid surfaceis within 1 mm but not touching the bottom edge of the film. Thealignment and position of the film may be easily determined byobservation of the reflection of the film edge in the liquid surface.After adjustment of the microbalance to tare away the weight of thesample the net force is recorded as an apparent mass reading. The finemotor on the platform is then used to raise the liquid surface at aspeed of about 2.5 μm per second. When the liquid makes contact with thefilm edge a force due to the adhesion tension is recorded. By means ofthe continued elevation of the platform the film is slowly immersed to adepth of about 0.4 cm at which point the test is discontinued and theplatform is returned to its initial level.

During the immersion, random fluctuations in the force are observed dueto inhomogeneities on the film surface while the average force decreasesgradually because of the effect of buoyancy. The wetting force isdetermined by extrapolation of a line drawn through the force readingback to the point where initial contact of the film with the surface wasmade. At this point buoyancy does not contribute to the force. Theperimeter of the film edge is then determined by careful measurement ofthe length of the bottom edge and the thickness of the film by means ofa caliper and micrometer. The adhesion tension is calculated accordingto the following formula: ##EQU16## where a=adhesion tension, dyne/cm

m=balance reading, g

g=acceleration of gravity (=977.2 cm/sec² at Kingsport, Tenn.)

w=width of bottom edge of sample, cm

t=film thickness, cm

Example 23--(TABLE II)

This is a comparative example which shows the surprisingly stronginfluence of increasing the adhesion tension from 32 to 60 dynes/cm onthe uphill flux for a series of different spontaneously wettable fibers.Sample 001-4B was identical to 001-7B except that 001-4B had 0.5% 70%PEG 600 monolaurate and 30% potassium lauryl phosphate applied duringspinning. This finish obviously inhibited an effective plasma treatmenton the sample. Compare the other paired samples to see the dramaticincrease in fluxes by increasing the adhesion tension. The specificdimensions for the spinneret orifice of FIG. 35 were as follows: W₁ =100microns, θ=90°, S=10, R=50, T=20, U=1.3, V=50 (see FIG. 33). Thespecific dimensions for the spinneret orifice of FIG. 36 were asfollows: W₁ =100 microns, θ=90°, S=10, R=50, T=10, U=1.3, V=50 (see FIG.33).

Example 24

Any computing means can be used in the uphill flux test provided that ithas enough memory and speed. The computer is programmed in anyconventional way to carry out the steps of the uphill flux test. Theprogramming will be apparent from the previous description. A usefulsummary of the program is set forth in FIG. 54.

The specific computer program used specifically in the uphill flux testused in this invention is incorporated herein as follows: Language isMicrosoft "Quick Basic". ##SPC1##

                                      TABLE II                                    __________________________________________________________________________                    Fiber Properties                                                              Single Filament Wetting Parameters                                        Take-up                                                                           Finish      Specific.sup.2                                                                     Channel                                                  Speed                                                                             Applied in                                                                           Denier/                                                                            Volume                                                                             Width                                        Sample.sup.1                                                                      Spinneret                                                                             m/m Spinning, %                                                                          Filament                                                                           cc/gm                                                                              (microns)                                    __________________________________________________________________________    001-6A                                                                            FIG. 35 300 None    73  3.56 53.1                                             FIG. 35 300 70% PEG 600                                                                           73  3.56 53.1                                                         Monolaurate                                                                   30% Potassium                                                                 Lauryl                                                                        Phosphate                                                                     0.5%                                                          001-7B                                                                            FIG. 36 200 None   103  3.03 35.5                                             FIG. 36 200 70% PEG 600                                                                          103  3.03 35.5                                                         Monolaurate                                                                   30% Potassium                                                                 Lauryl                                                                        Phosphate                                                                     0.5%                                                          001-4B                                                                            FIG. 36 200 70% PEG 600                                                                          110  2.42 39.0                                                         Monolaurate                                                                   30% Potassium                                                                 Lauryl                                                                        Phosphate                                                                     0.5%                                                          003-1-1                                                                           Same as 001-6A                                                                            None             40.0                                             except drawn 2X                                                               and heatset at                                                                130° C.                                                            003-2-1                                                                           Same as 001-7B                                                                            None             23.1                                             except drawn 2X                                                               and heatset at                                                                130° C.                                                            __________________________________________________________________________    Fiber Properties                                                              Single Filament Wetting Parameters                                                Leg  Channel                                                                            Backbone                                                                           Initial        Adhesion                                        Thickness                                                                          Depth                                                                              Thickness                                                                          Velocity                                                                           Slope                                                                              Flux Tension                                     Sample.sup.1                                                                      (microns)                                                                          (microns)                                                                          (microns)                                                                          mm/sec                                                                             mm.sup.2 /sec                                                                      cc/gm/hr                                                                           dyne/cm                                     __________________________________________________________________________    001-6A                                                                            8.9  123  10.5 51   203  37.5.sup.p                                                                         60                                              8.9  123  10.5           0.8  32                                          001-7B                                                                            11.4 166  15.0           22.7.sup.p                                                                         60                                              11.4 166  15.0           3.1  32                                          001-4B                                                                            11.5 171  14.8           6.3.sup.p                                                                          35                                          003-1-1                                                                           7.0  91.4 7.9            32.4.sup.p                                                                         60                                          003-2-1                                                                           7.7  104  10.1           20.1.sup.p                                                                         60                                          __________________________________________________________________________     .sup.1 Polymer, 0.89 I.V., bright PET melt temperature 295° C.         quench air235 ft/min at 21" below spinneret.                                  .sup.2 Described in U.S. Pat. No. 4,245,001. P = Plasma treated. The          equipment used was the same as described in Example 1 hereof except a         Leesona winder was used for takeup.                                      

Example 24

This example shows the influence of channel width on uphill flux forfixed values of channel depth, leg width, material of choice andadhesion tension. Notice the maximum flux occurs at a channel width ofapproximately 80 microns for the dimensions of the PET fiber shown (seeFIG. 37).

Example 25

The influence of increasing the adhesion tension is shown dramaticallyin Example 23. This example shows how the uphill flux varies for a givenfiber material and geometry with adhesion tension (see FIG. 38). Inother words, for each adhesion tension at a fixed leg width and channeldepth, there is an optimum channel width which maximizes the flux.

Example 26

Hydrofil® nylon polymer designated SCFX by Allied-Signal, Inc. was spuninto fiber using the spinneret shown in FIG. 41 at 270° C. using wateras the finish applied. The "W" shown in FIG. 41A was 100 microns. Thecross-section of the fiber is also shown in FIG. 41. These fibersyielded a flux of 10.4 cc/gm/hr in the uphill test. The measuredadhesion tension was about 50 dynes/cm. Thus, this particular nyloncoupled with spinning conditions which yielded a good cross-section witha channel width of 44 microns produced a very high flux without anysurface finish or treatment.

Example 27

PET fiber similar to that in Example 23 was spun at 70 dpf.Approximately 3 grams of this sample were placed in a metal frame(approximately 15 inches long and 8 inches wide) and shipped to PlasmaScience, Inc. for treatment. First, the PET sample was treated withArgon plasma for about 2 minutes. The pressure in the chamber of thePlasma Science PS-0500 plasma surface treatment system was reduced toabout 0.3 tort. Power input to the unit was maintained at about 300watts. Excitation power was provided by the RF generator operating at13.56 MHz. Subsequently, the RF generator was turned off, acrylic acidvapors were introduced in the chamber for about 10 minutes, and thepressure was reduced to 0.02 torr. The acrylic acid vapors reacted withthe plasma treated PET fiber surface resulted in an acrylic acid graftedPET surface. These fibers gave a 7.4 cc/gm/hr flux in the uphill test.

Example 28

A 0.90 I.V. PET polymer was extruded on the system described in Example1 at 289° C. The cross flow air velocity was 115 feet/minute and thetakeup velocity was 800 feet/minute. Lubricant (5% active solution ofMilease T in water) was applied from a double kiss roll arrangement inspinning at 10 rpm. The diameter of the ceramic oil roll was 150 mm. A10 hole radial design spinneret was used to spin the fiber. Thespinneret was identical to that shown in FIG. 43 except that the widthof the "H" slot was 25W instead of 50W and W=0,100 mm. The extrusionrate was adjusted to make a nominal 75 dpf fiber. The resulting channeldimensions were 55 microns channel width, 7.3 microns leg width, and 172microns channel depth. This fiber produced a flux of 7.6 cc/g/hr. in theuphill flux test.

Example 29

This example shows a stuffer box crimped fiber with a distorted crosssection and a helical crimped fiber without a distorted cross section.The stuffer box crimped sample was listed as sample SW-181-1A, and thehelical crimped sample was listed as sample SW-186. Both samples were ofa two channel H cross section.

Sample SW-181-1A for stuffer box crimping was melt spun from 0.68 IVpoly(ethylene terephthalate) polymer on a unit using a spinneret I 1045to make a 38 denier per filament continuous filament fiber. Spinneret I1045 is described in FIG. 42. The "W" in FIG. 42C was 84 microns. Thespinneret holes were oriented such that the cross-flow quench air wasdirected toward the open end of the H at a velocity of 180 foot perminute as the fibers traveled down the cabinet. The fiber was spun at1000 meters per minute with a melt temperature of 285° C. and lubricatedwith Hypermer A109 lubricant (a modified polyester surfactant sold byICI Americas, Inc.).

Sample SW-186 for helical crimping was melt spun from 0.62 IVpoly(ethylene terephthalate) polymer on a unit using spinneret I 1039 tomake a 30 denier per filament continuous filament fiber. Spinneret I1039 is described in FIG. 43. The "W" in FIG. 43A was 100 microns. Thespinneret holes were oriented in a radial pattern on the face of thespinneret. Cross-flow quench air was directed at a velocity of 125 footper minute toward the fiber bundle as the fibers traveled down thecabinet. The fiber was spun at 1500 meters per minute with a melttemperature of 288° C. and lubricated with PM 13430 lubricant comprising49% polyethylene glycol (PEG) 600 monolaurate, polyoxyethylene (13.64)monolaurate, 49% polyethylene glycol (PEG) 400 monolaurate,polyoxyethylene (9.09) monolaurate, and 2% 4-cetyl-4-ethylmorpholiniumethosulfate (antistat). The equipment used was the same as described inExample 1 except that a Leesona winder was used for take-up.

A conventional two stage drafting line was used to process the SW-181-1Aand SW-186 as-spun fiber.

The packages of SW-181-1A feed yarn were placed on creel posts andformed into a tow. The tow was guided to the first set of rolls runningat 18 meters per minute. The tow left the first rolls and was submergedin a water bath having a water temperature of 74° C. The tow was guidedfrom the water bath to the second set of rolls which were running at 35meters per minute. The tow continued from the second rolls through asteam chamber set at 130° C. to the third rolls running at 45 meters perminute. The tow then went over a series of heatset rolls set at 180° C.to heatset the fiber with tension. The tow then went through a stufferbox crimper and was placed onto a dryer apron which carried the tow intoan oven for drying the fiber at 100° C. for 5 minutes. In this case,Hypermer A109 lubricant was applied to the tow at the crimper. Thestuffer box crimped fiber had a distorted cross section as shown in FIG.44.

The packages of feed yarn were placed on creel posts and formed into atow. The tow was guided to the first set of rolls running at 26 metersper minute. The tow left the first rolls and was submerged in a waterbath having a water temperature of 70° C. The tow was guided from thewater bath to the second set of rolls which were running at 39 metersper minute. The tow continued from the second rolls through a steamchamber set at 130° C. to the third rolls running at 60 meters perminute. The tow then went to a puddling jet which placed the tow onto adryer apron which carried the tow into an oven for shrinking withouttension at 150° C. for 5 minutes. In this case, PM 13430 lubricant wasapplied to the tow as it exited the dryer. Helical crimped fiber formedduring the shrinking step in the oven. The helical crimped fiber did nothave a distorted cross section as shown in FIG. 45.

Example 30

This example shows the importance of having the spinneret hole shapesoriented in specified configurations relative to the cross-flow quenchair when making helical crimped fibers.

Sample X21766-177-1 was melt spun from 0.70 IV poly(ethyleneterephthalate) polymer using spinneret I 1046 on a unit to make a 51denier per filament continuous filament fiber. Spinneret I 1046 isdescribed in FIG. 46. The "W" in FIG. 46C was 84 microns. The spinneretholes were oriented such that the cross-flow quench air was directedtoward the open end of the H at a velocity of 111 feet per minute as thefibers traveled down the cabinet. A drawing of the quench air directionrelative to the spinneret hole is shown in FIG. 47. The fiber was spunat 1000 meters per minute with a melt temperature of 285° C. andlubricated with PM 13430 lubricant. The equipment used was the same asdescribed in Example 1 except that a Leesona winder was used fortake-up.

As-spun sample X21766-177-1 was drafted by guiding the yarn to a firstset of rolls running at 25 meters per minute. The fiber left the firstrolls and was submerged in a water bath having a water temperature of70° C. The fiber was guided from the water bath to the second set ofrolls which were running at 47.5 meters per minute. The fiber continuedfrom the second rolls through a steam chamber set at 145° C. to thethird rolls running at 52.5 meters per minute. The fiber was then woundonto a package and identified as sample number X21766-183-1A. A denierreel was used to unwind fiber from the package to make a skein of yarn.The skein was placed in a forced air oven set at 150° C. for 5 minutesand allowed to shrink without tension. Acceptable helical crimp did notform during the shrinking step in the oven. The fiber containedcrenulated sections with a distorted cross-section.

Sample X21766-176-1 was melt spun from 0.70 IV poly(ethyleneterephthalate) polymer using spinneret I 1047 on a unit to make a 51denier per filament continuous filament fiber. Spinneret I 1047 isdescribed in FIG. 48. The "W" in FIG. 48C was 84 microns. The spinneretholes were oriented such that the cross-flow quench air was directedtoward one side of the H at a velocity of 111 feet per minute as thefibers traveled down the cabinet. A drawing of the quench air directionrelative to the spinneret hole is shown in FIG. 47. The fiber was spunat 1000 meters per minute with a melt temperature of 285° C. andlubricated with PM 13430-lubricant. The equipment used was the same asdescribed in Example 1 except that a Leesona winder was used fortake-up.

As-spun sample X21766-176-1 was drafted by guiding the fiber to a firstset of rolls running at 25 meters per minute. The yarn left the firstrolls and was submerged in a water bath having a water temperature of70° C. The fiber was guided from the water bath to the second set ofrolls which were running at 52.5 meters per minute. The fiber continuedfrom the second rolls through a steam chamber set at 145° C. to thethird rolls running at 57.5 meters per minute. The fiber was then woundonto a package and identified as sample X21766-181-1A. A denier reel wasused to unwind fiber from the package to make a skein of yarn. The skeinwas placed in a forced air oven set at 150° C. for 5 minutes and allowedto shrink without tension. Helical crimped fiber formed during theshrinking step in the oven. The helical crimped sample had 7.4 crimpsper inch with a crimp amplitude of 0.46 mm. The sample had an a bulkylook and an acceptable hand.

Example 31

This example shows that helical crimped fiber without a distorted crosssection will improve fluid movement when compared to a stuffer boxcrimped sample with a distorted cross-section.

Spontaneously wettable polyester fibers identified as SW-188 were meltspun from 0.78 IV poly(ethylene terephthalate) polymer using spinneretI-1039 on a unit to make a 29 denier per filament continuous filamentfiber. Spinneret I 1039 is described in FIG. 43. The spinneret holeswere oriented in a radial pattern on the face of the spinneret withcross-flow quench air directed at a velocity of 100 foot per minutetoward the fiber bundle as the fibers traveled down the cabinet. Thefiber was spun at 1500 meters per minute with a melt temperature of 292°C. and lubricated with PM 13430 lubricant. The equipment used was thesame as described in Example 1 except that a Leesona winder was used fortake-up.

A conventional two stage drafting line was used to process the as-spunfiber.

Helical crimped fiber without a distorted cross-section was first made.The as-spun packages were placed on creel posts and formed into a tow.The tow was guided to a first set of rolls running at 20 meters perminute. The tow left the first rolls and was submerged in a water bathhaving a water temperature of 73° C. The tow was guided from the waterbath to the second set of rolls which were running at 35 meters perminute. The tow continued from the second rolls through a steam chamberset at 135° C. to the third rolls running at 43 meters per minute. Thetow then went to a puddling jet which placed the tow onto a dryer apronwhich carried the tow into an oven for shrinking without tension at 150°C. for 5 minutes. PM 13430 lubricant was applied to the tow as it exitedthe dryer. Helical crimped fiber formed during the shrinking step in theoven. The helical crimped fiber did not have a distorted cross sectionas shown in FIG. 49.

Stuffer box crimped fiber with a distorted cross-section was then madefrom the as-spun packages. The as-spun packages were placed on creelposts and formed into a tow. The tow was guided to a first set of rollsrunning at 20 meters per minute. The tow left the first rolls and wassubmerged in a water bath having a water temperature of 73° C. The towwas guided from the water bath to the second set of rolls which wererunning at 35 meters per minute. The tow continued from the second rollsthrough a steam chamber set at 135° C. to the third rolls running at 43meters per minute. The tow then went through a stuffer box crimper andwas then heatset without tension at 150° C. for 5 minutes. In this case,LK 5570 lubricant was applied to the tow just before the crimper. Thestuffer box crimped fiber did have a distorted cross section as shown inFIG. 50.

The single filament wettability test is a useful test for characterizingthese materials. Filaments from each type of crimp were tested sixtytimes for single filament wetting, and the results are shown below.

    ______________________________________                                                       Stuffer Box                                                                             Helical Crimped                                                     Crimped   Crimped                                              ______________________________________                                        Average Velocity                                                                             14.7      19.7                                                 (mm/sec)                                                                      Average Slope  9.7       32.3                                                 (mm*mm/sec)                                                                   ______________________________________                                    

This data is significant at the 95% confidence level and shows that thehelical crimped sample is better for moving fluids than the stuffer boxcrimped sample.

Example 32

This example shows a helical crimped fiber made using an I-1005spinneret.

Spontaneously wettable polyester fibers were melt spun from 0.62 IVpoly(ethylene terephthalate) polymer using spinneret I 1005 on a unit tomake a 20 denier per filament continuous filament fiber. Spinneret I1005 is described in FIG. 51 and FIG. 52. The slot width in FIG. 51A was100 microns, and the numbers on the figure are multiples of the slotwidth. The spinneret holes were oriented in a diagonal pattern on theface of the spinneret with cross-flow quench air directed at a velocityof 250 feet per minute toward the fiber bundle as the fibers traveleddown the cabinet. The fiber was spun at 1500 meters per minute with amelt temperature of 280° C. and lubricated with PM 13430 lubricant.

A conventional two stage drafting line was used to process the fiber.

Twelve packages of feed yarn were placed on creel posts and formed intoa tow. The tow was drafted by guiding the tow to a first set of rollsrunning at 16 meters per minute. The yarn left the first rolls and wassubmerged in a water bath having a water temperature of 70° C. The fiberwas guided from the water bath to the second set of rolls which wererunning at 38 meters per minute. The fiber continued from the secondrolls through a steam chamber set at 150° C. to the third rolls runningat 40 meters per minute. The tow then went to a puddling jet whichplaced the tow onto a dryer apron which carried the tow into an oven forshrinking without tension at 150° C. for 1 minute. Helical crimped fiberformed during the shrinking step in the oven. The helical crimped samplewas labeled X21741-060-3 and had 8.2 crimps per inch with a crimpamplitude of 0.26 mm. The sample had an a bulky look and an acceptablehand.

                                      TABLE III                                   __________________________________________________________________________    3 CM SYN-URINE FLUX FOR SELECTED SURFACTANTS                                  __________________________________________________________________________    Oil Roll                                                                          HPMA109                                                                             PM 13430                                                                           BRIJ35                                                                              BRIJ99                                                                              BRIJ700                                                                              MIL T                                                                              G1300 G1350 G144  TW60                 RPM 5% in H.sub.2 O                                                                     E-5  5% in H.sub.2 O                                                                     5% in H.sub.2 O                                                                     5% in H.sub.2 O                                                                      3% Active                                                                          5% in H.sub.2 O                                                                     5% in H.sub.2 O                                                                     5% in                                                                               5% in H.sub.2        __________________________________________________________________________                                                             O                     7  --    84.7 --    --    --     49.7 86.5  --    128.4 98.4                  7  --    106.2                                                                              --    --    --     77.4 76.3  --    128.0 171.3                10  --    --   --    --    --     --   --    133.9 --    --                   10  --    --   --    --    --     --   --    117.2 --    --                   15  152.1 113.4                                                                              110.4 151.5 103.5  107.5                                                                              109.5 101.9 109.1 100.0                15  121.5 95.3 145.1 184.7 97.6   127.7                                                                              137.6 92.3  99.4  93.2                 25  114.7 114.8                                                                              124.5 144.7 109.6  144.6                                                                              132.9 134.5 52.9  117.5                25  118.0 104.1                                                                              165.5 129.0 115.6  161.0                                                                              167.1 92.8  72.6  111.2                35  156.4 91.8 150.1 106.3 106.3  132.2                                                                              148.7 102.6 43.6  119.7                35  117.4 64.0 156.6 144.3 93.8   190.5                                                                              152.1 101.8 47.4  118.8                45  137.0 117.9                                                                              165.8 111.4 105.9  131.2                                                                              155.4 80.3  --    101.0                45  167.4 --   170.8 120.1 101.3  136.0                                                                              175.4 92.8  --    94.2                 55  101.2 85.9 176.6 133.6 88.0   141.7                                                                              140.9 --    --    92.8                 55  143.6 85.3 161.0 160.6 116.6  134.1                                                                              160.5 --    --    94.6                 Best                                                                              167.4 117.9                                                                              176.6 184.7 116.6  190.5                                                                              175.4 134.5 128.4 171.3                Six 156.4 114.8                                                                              170.8 160.6 115.6  161.0                                                                              167.1 133.9 128.0 119.7                    152.1 113.4                                                                              165.8 151.5 109.6  144.6                                                                              160.5 117.2 109.1 118.8                    143.6 106.2                                                                              165.5 144.7 106.5  141.7                                                                              155.4 102.6 99.4  117.5                    137.0 104.1                                                                              161.0 144.3 105.9  136.0                                                                              152.1 101.9 72.6  111.2                    121.5 95.3 156.6 133.6 103.5  134.1                                                                              148.7 101.8 52.9  101.0                Avg.                                                                              146.3 108.6                                                                              166.1 153.2 109.6  151.3                                                                              159.9 115.3 98.4  123.3                Best 6                                                                        Std.                                                                              16.1  8.4  7.1   17.8  5.4    21.4 10.0  15.8  30.4  24.6                 Dev.                                                                          Best 6                                                                        __________________________________________________________________________    Oil Roll                                                                          IL2535L1                                                                             IL2535L2                                                                            RX20   RX30  RX31   TK1674                                                                              TL1914 IL2535L3                                                                            IL2535L4              RPM 5% in H.sub.2 O                                                                      5% in H.sub.2 O                                                                     5% in H.sub.2 O                                                                      5% in H.sub.2 O                                                                     5% in H.sub.2 O                                                                      5% in H.sub.2 O                                                                     5% in H.sub.2 O                                                                      5% in                                                                               5% in H.sub.2         __________________________________________________________________________                                                            O                      7  115.5  152.5 142.6  66.0  80.3   73.3  41.0   77.3  117.6                  7  77.0   104.5 121.6  103.8 89.6   72.9  55.9   91.0  88.8                  10  --     --    --     --    --     --    --     --    --                    10  --     --    --     --    --     --    --     --    --                    15  91.7   120.2 120.9  87.9  113.4  101.4 75.6   107.2 91.2                  15  107.8  117.8 143.0  74.7  95.1   122.3 67.8   100.3 89.2                  25  87.8   114.1 144.0  100.8 72.2   110.9 104.0  78.5  92.7                  25  91.1   121.9 148.9  112.0 86.2   167.6 82.6   99.7  72.4                  35  105.6  120.4 124.9  108.7 97.2   104.1 90.6   122.6 76.2                  35  157.6  115.6 118.7  101.8 83.4   94.6  98.2   83.4  85.5                  45  77.7   108.9 113.2  77.4  102.4  84.9  75.5   100.4 71.6                  45  104.8  98.4  111.6  91.3  112.0  97.0  95.9   75.8  86.9                  55  123.6  114.0 94.0   92.4  75.7   110.3 80.1   60.7  70.2                  55  101.0  116.4 103.0  72.3  87.0   123.6 69.6   57.6  78.5                  Best                                                                              157.6  152.5 148.9  112.0 113.4  167.6 104.0  122.6 117.6                 Six 123.6  121.9 144.0  108.7 112.0  123.6 98.2   107.2 92.7                      107.8  120.4 143.0  103.8 102.4  122.3 95.9   100.4 91.2                      105.6  120.2 142.6  101.8 97.2   110.9 90.6   100.3 89.2                      104.8  117.8 124.9  100.8 95.1   110.8 82.6   99.7  88.8                      101.0  116.4 121.6  92.4  89.6   104.1 80.1   91.0  86.9                  Avg.                                                                              116.7  124.9 137.5  103.3 101.6  123.2 91.9   103.5 94.4                  Best 6                                                                        Std.                                                                              21.5   13.7  11.3   6.8   9.5    23.0  9.3    10.7  11.5                  Dev.                                                                          Best 6                                                                        __________________________________________________________________________

                  TABLE IV                                                        ______________________________________                                        Relative Ranking of Selected Surfactants                                      Based on 3CM Flux Tests                                                       Surfactant   Relative Flux*                                                   ______________________________________                                        BRIJ35       166.1                                                            G1300        159.9                                                            BRIJ99       153.2                                                            MIL T        151.3                                                            HPMA109      146.3                                                            RX20         137.5                                                            IL2535L2     124.9                                                            TW60         123.3                                                            TL1674       123.2                                                            IL2535L1     116.7                                                            G1350        115.3                                                            BRIJ700      109.6                                                            PM 13430     108.6                                                            RX30         103.3                                                            IL2535L3     103.5                                                            RX31         101.6                                                            G1441        98.4                                                             IL2535L4     94.4                                                             TL1914       91.9                                                             ______________________________________                                         *(Avg. flux)/in cc/hr per gram                                           

                  TABLE V                                                         ______________________________________                                        Statistical Comparison of Selected Surfactants                                Based on 3CM Syn-Urine Flux Tests                                             ______________________________________                                        BRIJ 35:   AVG FLUX = 166 (cc/hr-gm), VAR = 49.8 (cc/hr-                                 gm).sup.2                                                          Equal to:  G1300 (0.82)*, BRIJ99 (0.71), MIL T                                           (0.78)                                                             Better than:                                                                             HPMA109, RX20, IL2535L2, TW60x**,                                             TL1674x, IL2535L1x, G1350, BRIJ700,                                           LK5570                                                             G1300:     AVG FLUX = 159, VAR = 99.8                                         Equal to:  BRIJ99 (0.90), MIL T (0.89), HPMA109                                          (0.67)                                                             Better than:                                                                             RX20, IL2535L2, TW60, TL1674, IL2535L1,                                       G1350, BRIJ700, LK5500                                             BRIJ99:    AVG FLUX = 153, VAR = 317                                          Equal to:  MIL T (0.95), HPMA109 (0.91), RX20 (0.65)                          Better than:                                                                             IL2535L2, TW60, TL1674, IL2535L1, G1350,                                      BRIJ700x, LK5570                                                   MIL T:     AVG FLUX = 151, VAR = 460                                          Equal to:  HPMA109 (0.93), RX20 (0.78), TW60 (0.60),                                     TL1674 (0.60)                                                      Better than:                                                                             IL2535L2, IL2535L1, G1350, BRIJ700x,                                          LK5570                                                             HPMA109:   AVG FLUX = 146, VAR = 258                                          Equal to:  RX20 (0.85, TW60 (0.61), TL1674 (0.60)                             Better than:                                                                             IL2535L2, IL2535L1, G1350, BRIJ700x,                                          LK5570                                                             RX20:      AVG FLUX = 138, VAR = 128                                          Equal to:  IL2535L2 (0.68), TW60 (0.81), TL1674                                          (0.79), IL2535L1 (0.60)                                            Better than:                                                                             G1350, BRIJ700, LK5570                                             IL2535L2:  AVG FLUX = 125, VAR = 187                                          Equal to:  TW60 (0.95), TL1674 (0.95), IL2535L1                                          (0.90), G1350 (0.85)                                               Better than:                                                                             BRIJ700, LK5570                                                    TW60:      AVG FLUX = 123, VAR = 603                                          Equal to:  TL1674 (0.95), IL2535L1 (0.93), G1350                                         (0.91), BRIJ700x (0.86), LK5570x                                   TL1674:    AVG FLUX = 123, VAR = 528                                          Equal to:  IL2535L1 (0.93), G1350 (0.91), BRIJ700x                                       (0.85), LK5500x (0.81)                                             IL2535L1:  AVG FLUX = 116, VAR = 462                                          Equal to:  G1350 (0.95), BRIJ700 (0.92), LK5570                                          (0.89)                                                             G1350:     AVG FLUX = 115, VAR = 248                                          Equal to:  BRIJ700x (0.91), LK5570 (0.88)                                     BRIJ700:   AVG FLUX = 110, VAR = 29                                           Equal to:  LK5570 (0.94)                                                      ______________________________________                                         *Beta value: probability that means are different when they have been         accepted as equal                                                             **x indicates that variances of the two surfactants being compared were       different (F test) and separate variances were used in the t test        

    ______________________________________                                        APPENDIX A to Example 32                                                      SYMBOL      SURFACTANT DESCRIPTION                                            ______________________________________                                        BRIJ35      Polyoxyethylene (23) lauryl ether (ICI)                                       HLB = 16.9                                                        BRIJ99      Polyoxyethylene (20) oleyl ether (ICI)                                        HLB = 15.3                                                        BRIJ700     Polyoxyethylene (100) stearyl ether (ICI)                                     HLB = 18.8                                                        G1300       G-1300 Polyoxyethylene glyceride ester                                        (ICI) Nionic surfactant HLB = 18.1                                G1350       "ATLAS" G-1350 (ICI) Polyoxylene-                                             polyoxypropylene-sorbitan linoleic                                            phthalic ester                                                    G-1441      G-1441 (ICI) Polyoxyethylene (40)                                             sorbitol, lanolin alcoholysis product                             HPMA109     Hypermer A109 (ICI) Modified Polyester                                        Surfactant (98%)/Xylene (2%) HLB = 13-15                          IL2535L1    IL-2535 "Xylene-free/TMA free" Hypermer                                       A109 (ICI) Modified polyester surfactant                                      (HA = high acid no.)                                              IL2535L2    IL-2535 "Xylene-free/TMA free" Hypermer                                       A109 (ICI) Modified polyester surfactant                                      (LA = low acid no.)                                               IL2535L3    IL-2535 "Xylene-free/TMA free" Hypermer                                       A109 (ICI) Modified polyester surfactant                                      (LA = low acid no.)                                               IL2535L4    IL-2535 "Xylene-free/TMA free" Hypermer                                       A109 (ICI) Modified polyester surfactant                                      (LA = low acid no.)                                               PM 13430    (Eastman Chemical Company)                                        MIL T       MILEASE T (ICI) Polyester/water/other                                         ingredients                                                       RX20        RENEX 20 (ICI) Polyoxyethylene (16) tall                                      oil (100%) (CAS-61791-002) HLB = 13.8                             RX30        RENEX 30 (ICI) Polyoxyethylene (12)                                           tridecyl alcohol (100%) (CAS 24938-91-8)                                      HLB = 14.5                                                        RX31        RENEX 31 (ICI) Polyoxyethylene (12)                                           tridecyl alcohol (100%) (CAS 24938-91-8)                                      HLB = 15.4                                                        TL-1674     TL-1674 (ICI) Polyoxyethylene (36) castor                                     oil (100%) (CAS 61791-12-6)                                       TL-1914     TL-1914 (ICI) Cocoamidopropyl Betaine                                         (CAS-61789-40-0)                                                  TW60        TWEEN 60 (ICI) Polyoxyethylene (20)                                           sorbitan monostearate HLB = 14.9                                  ______________________________________                                    

Example 33

Table III summarizes the result for 3 cm syn-urine flux tests performedon several surfactants. Values are tabulated as cc of fluid per hour pergram of fiber. The tests in Table III were conducted to determine therelative performance of these surfactants in transporting aqueous-basedfluids. Most of these surfactants were applied from a 5 weight percentsolution in water. A range of oil roll speeds was used to cover arelatively wide range of application of each surfactant in an attempt tooptimize flux performance.

Examination of the data in Table III reveals that the flux performanceof most of the surfactants is relatively flat over the range of oil rollspeeds used, although there may be some evidence of decreasedperformance at low oil roll speed for Milease T and some evidence ofdecreased performance at high oil roll speed for G-1441. For thesereasons, the best six points were selected for each surfactant asrepresentative of optimum performance. The mean and standard deviationof the selected values for each surfactant are also tabulated in TableIII.

The average flux for each Surfactant was used to calculate the relativeflux ranking shown in Table IV. This was done by dividing each averagevalue by the maximum average value, which was 166 for BRIJ 35.

Statistical tests were performed to compare the means for all pairs ofsurfactants above the dotted line in Table IV using a confidence levelof 95 percent. These results are summarized in Table V. Beta values, theprobability that the means are different when they have been accepted asequal, are shown in parentheses. Additionally, a small x has been usedto indicate when the variances of the two surfactants being compared arestatistically different (determined by an F test). PM 13430 was selectedas the lower limit for mean comparisons.

Example 34--Measurement of Advancing Contact Angle

The technique (Modified Wilhelmy Slide Method) used to measure theadhesion tension can also be used to measure the Advancing Contact Angleθ_(a). The force which is recorded on the microbalance is equal to theadhesion tension times the perimeter of the sample film.

    Force=Adhesion Tension X Perimeter=γCos θ.sub.a X p

Where γ is the surface tension of the fluid (dynes/cm)

θ_(a) is the advancing contact angle (degree)

p is the perimeter of the film (cm) or solving for θ_(a) : ##EQU17##

For pure fluids and clean surfaces, this is a very simple calculation.However, for the situation which exists when finishes are applied tosurfaces and some of this finish comes off in the fluid the effective γis no longer the γ of the pure fluid. In most cases the materials whichcome off are materials which lower significantly the surface tension ofthe pure fluid (water in this case). Thus, the use of the pure fluidsurface tension can cause considerable error in the calculation ofθ_(a).

To eliminate this error a fluid is made up which contains the pure fluid(water in this case) and a small amount of the material (finish) whichwas deposited on the sample surface. The amount of the finish addedshould just exceed the critical micelle level. The surface tension ofthis fluid is now measured and is used in the θ_(a) calculation insteadof the pure fluid γ. The sample is now immersed in this fluid and theforce determined. θ_(a) is now determined using the surface tension ofthe pure fluid with finish added and the Force as measured in the purefluid with finish added. This θ_(a) can now be used in (1-X θ_(a))expression to determine if the expression is negative.

Example 35 (Base Fiber Preparation)

Poly(ethylene terephthalate) (PET) polymer of 0.69 I.V. was used in thisexample. I.V. is the inherent viscosity as measured at 25° at a polymerconcentration of 0.50 g/100 milliliters (mL) in a suitable solvent suchas a mixture of 60% phenol and 40% tetrachloroethane by weight. Thepolymer was dried to a moisture level of ≦0.003 weight percent in aPatterson Conaform dryer at 120° C. for a period of 8 hours. The polymerwas extruded at 285° C. through an Egan extruder, 1.5-inch diameter,with a length to diameter ratio of 28:1. The fiber was extruded througha twelve orifice spinneret wherein each orifice is as shown in FIG. 33wherein

W₁ =0.100 mm

P=50

V=50

R=50

U=1.3

S=5

θ=90°

The polymer throughput was about 9 pounds (lb)/hour. The average airquench system had a cross-flow configuration. The quench air velocitywas 93 feet (ft)/min. No spinning lubricant was applied to the as-spunyarn. Fibers of 78 dpf (denier per filament) were wound at 650 metersper minute (MPM) on a Leesona winder.

The surfactants listed in Table IV were applied to the unlubricated basefiber by feeding the yarn at a speed of 20 meters per minute across akiss roll of approximately 21/16 inch diameter. The kiss roll speedscovered a range of 15-55 rpm and the depth of immersion of the kiss rollin the surfactant solutions was 1/4 to 3/8 inch. The yarn break angleover the kiss roll was approximately 2-5 degrees.

Example 36--3 cm Uphill Flux Test Scope and Significance

This method is used to determine the fluid transport rate of capillarytransport materials from a reservoir of synthetic urine fluid along anincline to an absorbant. This computer monitored version of the methodautomatically measures the fluid uptake of the test materials andprovides a profile of the weight gain of the transport and absorbantstorage materials with time. The spontaneous movement of the fluid upthe incline and through the transport material is a quantitative measureof the surface and capillary forces acting on the fluid in opposition togravity. Uphill transport testing provides a means of comparing ratedifferences due to the type and size of capillary transport materials aswell as surface treatments and geometries. The test can also be used toevaluate the effects of test fluid surface tension as well as differentabsorbant materials. Finally, the test can be modified to simulatein-use conditions such as removing the reservoir and replacing it laterto simulate multiple urine additions.

Summary of Method

The uphill transport test is used to determine the fluid transport rateof capillary transport materials from a reservoir of synthetic urinetest fluid along a 10 cm long ramp to an absorbant on an attachedplatform at 3 cm height. Once the prepared specimen is mounted on theplatform/incline, the operator initiates the test according to theinstructions given by the computer program by placing the lower end ofthe transport material in the reservoir of fluid. The test continues for45 minutes or until terminated by the operator.

Definitions

The terms employed in this method are commonly used in normal laboratorypractice and require no special comment.

Safety Precautions

Normal safety precautions and safe handling practices should beobserved.

Sources of Error

Fluid transport is very surface and geometry dependent. Surfacecontamination should be avoided and sample handling should be minimized.

Condition all fiber and fabric samples, including the storage orabsorbant material, at least overnight in the laboratory before testingso that the moisture content is controlled by the relative humidity inthe laboratory.

The balance is very sensitive to fluid movement in the two reservoirs.Because the fluid transported by the test specimen is the measuredresponse of the test, an accurate tare weight of the fluid before thetest is started is essential. The computer does not take this tareweight reading until the specimen to be tested has been identified tothe computer and the label is accepted as correct by the operator.Therefore, prior to this time in the program, adjustments in thespecimen or test apparatus can be made without affecting the results.All adjustments must be made prior to this point in the testingprocedure.

Apparatus

A schematic representation of the apparatus used is in FIG. 39.

Reagents and Materials

SYN-URINE test fluid from Jayco

Pharmaceuticals (dyed with food coloring to aid observation)

Transport material of choice--in most cases this will be a sheet of PETfilaments

Absorbant or storage material, such as Bounty® towels or diaper coresections

Calibration and Standardization

Sample Preparation

Weigh a quantity of transport material precut to 20 cm length. Pull outa 9 cm length of Saran Wrap from its 12-inch wide dispenser box. Trimthe 111/2-inch wide wrap to 7 inches which is just the right size toplace around the transport material from the bottom or back side to thetop side with the ends of the wrap just meeting on the top for minimumoverlap (1/8-1/4 inch). Wrap loosely with Saran Wrap with about 21/2 cmof transport material sticking out from the end to be placed in thereservoir and with 81/2 cm sticking out from the end to be placed in theabsorbant. The resulting area of transport material covered with wrapwill be 9 cm length by 2 inch width. This covering minimizes evaporationfrom the transport material between the reservoir and the absorbant. Cutthe absorbant material of choice to 2 inch ×2 inch size.

Mount the covered transport material on the ramp with its previouslyassembled absorbant or assemble the transport material/absorbant layerson the ramp. Be sure the filled reservoir has been previously coveredwith stiff paper or cardboard so the 2-5 cm tail of the transportmaterial will not enter the fluid until the computer has been set up andis ready to start the data collection process. Once the absorbant is inplace on the horizontal part of the ramp, apply a load weight over theabsorbant (usually 0.5 psi).

Procedure

After turning on the computer, note the test menu and the C> prompt.Type "date" and enter the current date Return!. Type "UP" to start thetest program. Follow the instructions on the computer screen. Stop afteryou have labeled the sample to be tested. Accepting the labeling ascorrect will cause the computer to read the balance, and this must notoccur until the balance has stabilized with the test specimen and anyweights completely in place.

The test is started once the balance is stable by removing the reservoircover and allowing the transport material to enter the transport fluid.Press Return! when this occurs to start the computer program thatcollects the weight data.

The computer program is designed so that two transport processes arefollowed. The first one is when the fluid moves up the incline of theramp until the fluid front just reaches the absorbant at the top of theincline. This is the "induction" process. The computer must know whenthe fluid reaches the absorbant material. Pressing the F5 key tells thecomputer to calculate the induction process and to begin collecting datafor the "transport" process that occurs as the fluid moves in theabsorbant material at the top of the ramp.

At the end of the test (45 minutes total or sooner if the test isterminated by the operator) enter the weight of the transport materialas requested by the computer. The computer calculates the appropriatetimes and flux values and puts the results on the printer. The computeris programmed in any conventional way to carry out these calculations.The specific program used in the Examples of this invention isexemplified in Example 24.

Example 37

Fibers were prepared in accordance with the conditions found in U.S.Pat. No. 4,707,409, dated Nov. 17, 1987 by Phillips, et al. Inparticular, the cross-sections as represented by FIGS. 3, 5 and 7 wereprepared. The same lubricant as used in U.S. Pat. No. 4,707,409 wasused. The same spinnerets as shown in U.S. Pat. No. 4,707,409 were usedto form the fiber. The specific dimensions of the spinneret orificeswere the same as in U.S. Pat. No. 4,707,409. The fiber as represented bythe cross-section in FIG. 3 had a value for the "X" parameter of about1.8, O_(a) of about 22 degrees, and a cos O_(a) of about 0.9.Hypothetical filament cross-section 78 of U.S. Pat. No. 4,707,409 has anX parameter of 1.53. The values for O_(a) and cos O_(a) are the same asthose in FIG. 3 discussed above for section 78.

Example 38

Determination of Crimp Amplitude and Crimp Frequency

This describes the determination of crimp amplitude and crimp frequencyfor fibers in which the crimp is helical (3-dimensional).

The sample is prepared by randomly picking 25 groups of filaments. Onefilament is picked from each group for testing. Results are the averageof the 25 filaments.

A single fiber specimen was placed on a black felt board next to a NBSruler with one end of the fiber on zero. The relaxed length (Lr) wasmeasured.

The number of crimp peaks (N) were counted with the fiber in the relaxedlength. Only top or bottom peaks were counted, but not both. Half peaksat both ends were counted as one. Half counts were rounded up.

The single fiber specimen is grasped with tweezers at one end and heldat zero on the ruler, and the other end was extended just enough toremove crimp without stretching the filament. The extended length (Le)was measured.

Definitions

Crimp Frequency=The number of crimps per unit straight length of fiber.

Crimp Amplitude=The depth of the crimp, one-half of the total height ofthe crimp, measured perpendicular to the major axis along the centerline of the helically crimped fiber.

Calculations

For a true helix of pitch angle φ having N total turns, a relaxed lengthLr, and an extended (straight) length Le, the following equations apply:

    Le cos φ=Nπ(2A)

    Le sin φ=Lr

where A is the previously defined crimp amplitude. From these equations,A is readily calculated from the measured values of Lr, Le, and N asfollows: ##EQU18## Crimp frequency (C) as previously defined iscalculated as follows: ##EQU19## When Le and Lr are expressed in inches,crimp amplitude has units of inches and crimp frequency has units ofcrimps per inch.

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention. Moreover, all patents, patent applications (published orunpublished, foreign or domestic), literature references or otherpublications noted above are incorporated herein by reference for anydisclosure pertinent to the practice of this invention.

We claim:
 1. A process for helically crimping a synthetic fiber having across-sectional shape with a major axis and a minor axis of symmetrycomprising the steps of:(a) passing a molten polymer capable of forminga fiber through a spinneret hole forming a spun polymer, wherein thespinneret hole shape and the cross-sectional shape of the spun polymerhave a major and a minor axis of symmetry; (b) quenching the spunpolymer with air forming a fiber, wherein the air flows perpendicular tothe major axis of symmetry of the cross-sectional shape of the spunpolymer; (c) applying a lubricant to the fiber; (d) taking up the fiber;(e) drafting the fiber; and (f) relaxing the drawn fiber forming ahelical crimp.
 2. The process of claim 1 wherein step (b) the flow ofthe air is made perpendicular to the major axis by orienting thespinneret hole.
 3. The process of claim 1 further comprising betweenstep (e) and (f) applying an additional amount of the lubricant andwherein the molten polymer is poly(ethylene terephthalate), thelubricant is hydrophilic and the drawn fiber is relaxed in a heatedchamber.